when we call FilePath.chmod in plugin on AIX machine we get the following:
(Linux works fine)

hudson.remoting.Channel@7d88c3cf:ams80035_ep5612b
at hudson.FilePath.act(FilePath.java:749)
at hudson.FilePath.act(FilePath.java:735)
at hudson.FilePath.chmod(FilePath.java:1079)
at com.amdocs.hudson.plugins.xpi.XPIInstallationBuilder.killJavaProccesses(XPIInstallationBuilder.java:699)
at com.amdocs.hudson.plugins.xpi.XPIInstallationBuilder.deleteInstallationAccountContents(XPIInstallationBuilder.java:816)
at com.amdocs.hudson.plugins.xpi.XPIInstallationBuilder.preInstallationPreparation(XPIInstallationBuilder.java:737)
at com.amdocs.hudson.plugins.xpi.XPIInstallationBuilder.perform(XPIInstallationBuilder.java:235)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:603)
at hudson.model.Build$RunnerImpl.build(Build.java:172)
at hudson.model.Build$RunnerImpl.doRun(Build.java:137)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:417)
at hudson.model.Run.run(Run.java:1339)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:140)
Caused by: java.io.IOException: Remote call on ams80035_ep5612b failed
at hudson.remoting.Channel.call(Channel.java:638)
at hudson.FilePath.act(FilePath.java:742)
... 15 more
Caused by: java.lang.UnsatisfiedLinkError: jnidispatch (/com/sun/jna/aix-ppc/libjnidispatch.a) not found in resource path
at com.sun.jna.Native.loadNativeLibraryFromJar(Native.java:703)
at com.sun.jna.Native.loadNativeLibrary(Native.java:680)
at com.sun.jna.Native.<clinit>(Native.java:108)
at java.lang.J9VMInternals.initializeImpl(Native Method)
at java.lang.J9VMInternals.initialize(J9VMInternals.java:196)
at hudson.util.jna.GNUCLibrary.<clinit>(GNUCLibrary.java:105)
at java.lang.J9VMInternals.initializeImpl(Native Method)
at java.lang.J9VMInternals.initialize(J9VMInternals.java:196)
at hudson.FilePath$20.invoke(FilePath.java:1081)
at hudson.FilePath$20.invoke(FilePath.java:1079)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:1899)
at hudson.remoting.UserRequest.perform(UserRequest.java:114)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:270)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:432)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:284)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:678)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:703)
at java.lang.Thread.run(Thread.java:811)

Issue JENKINS-8155 I think deals with the same issue.
and Issue JENKINS-4820