I have tested IBM Alert Portlet in WSAD 5.1.2 with Websphere Portal V5.0 Tes
t Environment.
But whenever i install this Alert Portlet on Websphere portal server 5.0,and
 include these portlets(Alert Generator and Alert Viewer), it throws error o
n page.
This portlet is unavailable. If the problem persists, please contact the por
tal administrator.

WPS Log:
Nested Exception is com.ibm.ws.webcontainer.servlet.LoadTargetServletFailure
: Failed to load target servlet [Alert Generator]
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcherInfo.calculateInfo(
WebAppRequestDispatcherInfo.java:216)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcherInfo.<init>(WebAppR
equestDispatcherInfo.java:59)
at com.ibm.ws.webcontainer.webapp.WebApp.getRequestDispatcher(WebApp.java:14
35)
at com.ibm.ws.webcontainer.webapp.WebApp.getRequestDispatcher(WebApp.java:13
97)
at com.ibm.wps.pe.om.definition.impl.ServletDefinitionImpl.getRequestDispatc
her(ServletDefinitionImpl.java:157)....
...........

SystemOut Log:
java.lang.LinkageError: Class org/apache/jetspeed/portlet/Portlet violates l
oader constraints:  definition mismatch between parent and child loaders
at org.apache.jetspeed.portlet.Portlet.init(Portlet.java:442)
at com.ibm.ws.webcontainer.servlet.StrictServletInstance.doInit(StrictServle
tInstance.java:82)
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet._init(StrictLifecy
cleServlet.java:147)
at com.ibm.ws.webcontainer.servlet.PreInitializedServletState.init(StrictLif
ecycleServlet.java:270)
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet.init(StrictLifecyc
leServlet.java:113)
at com.ibm.ws.webcontainer.servlet.ServletInstance.init(ServletInstance.java
:189)....
............

Can anybody please suggest what went wrong.

Thanks in advance..

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I have had the same problem- portlet works fine in development environment, 
but on server it fails. Did you resolve this problem?

Apologies for level of detail, here are parts of the stack trace:

##
2005.07.20 12:53:41.625 E com.ibm.wps.pe.pc.legacy.PortletContainerImpl init
Page
  PEPC1023E: Portlet com.ibm.wps.pe.om.window.impl.PortletWindowImpl@120700a
f could not be logged in. - StackTrace follows...

2005.07.20 12:53:41.625 E com.ibm.wps.pe.pc.legacy.PortletContainerImpl init
Page
  javax.portlet.PortletException
	at com.ibm.wps.pe.pc.legacy.PortletContainerImpl.callPortletMethod(PortletC
ontainerImpl.java(Compiled Code))
	at com.ibm.wps.pe.pc.legacy.PortletContainerImpl.initPage(PortletContainerI
mpl.java(Compiled Code))
	at
##
2005.07.20 12:53:41.627 E com.ibm.wps.pe.pc.legacy.PortletContainerImpl init
Page
  PEPC1024E: Portlet com.ibm.wps.pe.om.window.impl.PortletWindowImpl@120700a
f failed in method beginPage. - StackTrace follows...
##
2005.07.20 12:53:41.627 E com.ibm.wps.pe.pc.legacy.PortletContainerImpl init
Page
  javax.portlet.PortletException
	at com.ibm.wps.pe.pc.legacy.PortletContainerImpl.callPortletMethod(PortletC
ontainerImpl.java(Compiled Code))
	at com.ibm.wps.pe.pc.legacy.PortletContainerImpl.initPage(PortletContainerI
mpl.java(Compiled Code))
	at 
##
2005.07.20 12:53:41.643 E com.ibm.wps.engine.tags.PortletRenderTag doStartTa
g
  FWEN0066E: The portlet could not be rendered. - StackTrace follows...
##
Nested Exception is com.ibm.ws.webcontainer.servlet.LoadTargetServletFailure: Failed to load 
target servlet [ESSearchPortlet]
	at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcherInfo.calculateInfo
(WebAppRequestDispatcherInfo.java(Compiled Code))
	at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcherInfo.<init>(WebApp
RequestDispatcherInfo.java(Inlined Compiled Code))
	at etcetera etcetera 
##

2005.07.20 12:53:41.643 E com.ibm.wps.engine.tags.PortletRenderTag doStartTa
g
  javax.portlet.PortletException
	at com.ibm.wps.pe.pc.legacy.PortletContainerImpl.callPortletMethod(PortletC
ontainerImpl.java(Compiled Code))
	at com.ibm.wps.pe.pc.legacy.PortletContainerImpl.renderPortlet(PortletConta
inerImpl.java(Compiled Code))
	at com.ibm.wps.pe.pc.PortletContainerImpl.doRenderPortlet(PortletContainerI
mpl.java(Compiled Code))
	at com.ibm.wps.pe.ext.ppr.ParallelRenderManager.performService(ParallelRend
erManager.java(Compiled Code))
	at  .... etcetera etcetera

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