Question : Exception received when I execute my ant script

I am receiving the below exception when the below line is executed in a ant script,
  >

Exception message:
file:/home/automan/hudson/workspace/ContentUnix/executeTasks.xml:585: taskdef class ise.antelope.tasks.StringUtilTask cannot be found
   at org.apache.tools.ant.taskdefs.Definer.addDefinition(java.lang.ClassLoader, java.lang.String, java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.taskdefs.Definer.execute() (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.helper.ProjectHelperImpl$TaskHandler.finished() (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.helper.ProjectHelperImpl$AbstractHandler.endElement(java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.xerces.parsers.AbstractSAXParser.endElement(org.apache.xerces.xni.QName, org.apache.xerces.xni.Augmentations) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanEndElement() (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(boolean) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(boolean) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.DTDConfiguration.parse(boolean) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.DTDConfiguration.parse(org.apache.xerces.xni.parser.XMLInputSource) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.XMLParser.parse(org.apache.xerces.xni.parser.XMLInputSource) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.AbstractSAXParser.parse(org.xml.sax.InputSource) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.tools.ant.helper.ProjectHelperImpl.parse(org.apache.tools.ant.Project, java.lang.Object) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.ProjectHelper.configureProject(org.apache.tools.ant.Project, java.io.File) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.Main.runBuild(java.lang.ClassLoader) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.Main.start(java.lang.String[], java.util.Properties, java.lang.ClassLoader) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.Main.main(java.lang.String[]) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
Caused by: java.lang.ClassNotFoundException: ise.antelope.tasks.StringUtilTask
   at org.apache.tools.ant.AntClassLoader.findClassInComponents(java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.AntClassLoader.findClass(java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.AntClassLoader.loadClass(java.lang.String, boolean) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at java.lang.ClassLoader.loadClass(java.lang.String) (/lib/ssa/libgcj.so.4.0.0)
   at org.apache.tools.ant.taskdefs.Definer.addDefinition(java.lang.ClassLoader, java.lang.String, java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   ...16 more
--- Nested Exception ---
java.lang.ClassNotFoundException: ise.antelope.tasks.StringUtilTask
   at org.apache.tools.ant.AntClassLoader.findClassInComponents(java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.AntClassLoader.findClass(java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.AntClassLoader.loadClass(java.lang.String, boolean) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at java.lang.ClassLoader.loadClass(java.lang.String) (/lib/ssa/libgcj.so.4.0.0)
   at org.apache.tools.ant.taskdefs.Definer.addDefinition(java.lang.ClassLoader, java.lang.String, java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.taskdefs.Definer.execute() (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.helper.ProjectHelperImpl$TaskHandler.finished() (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.helper.ProjectHelperImpl$AbstractHandler.endElement(java.lang.String) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.xerces.parsers.AbstractSAXParser.endElement(org.apache.xerces.xni.QName, org.apache.xerces.xni.Augmentations) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanEndElement() (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(boolean) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(boolean) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.DTDConfiguration.parse(boolean) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.DTDConfiguration.parse(org.apache.xerces.xni.parser.XMLInputSource) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.XMLParser.parse(org.apache.xerces.xni.parser.XMLInputSource) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.xerces.parsers.AbstractSAXParser.parse(org.xml.sax.InputSource) (/usr/lib/lib-javax-xml-parsers-2.2.1.so)
   at org.apache.tools.ant.helper.ProjectHelperImpl.parse(org.apache.tools.ant.Project, java.lang.Object) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.ProjectHelper.configureProject(org.apache.tools.ant.Project, java.io.File) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.Main.runBuild(java.lang.ClassLoader) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.Main.start(java.lang.String[], java.util.Properties, java.lang.ClassLoader) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)
   at org.apache.tools.ant.Main.main(java.lang.String[]) (/usr/lib/lib-org-apache-tools-ant-1.5.2.so)

Could someone help my what am I missing here ? Do I need to locate any jar file from my ant script ?

Answer : Exception received when I execute my ant script

where have u put the jar for StringUtilTask
needs to go in ant's lib directory I think