Validation Error

I am experiencing following validation error, when executing some of my processes using Preprocessor extensions. Any clues??

An unexpected exception occurred. The reason was: Validation error occurred while processing “http://127.0.0.1:9982/Rhythmyx/../psx_cerffImage/rffImage.html?sys_revision=1&sys_contentid=36530&sys_transitionid=15&sys_command=workflow&WFAction=AgetoPublic&sys_workflowid=6”, validation error is: <?xml version=“1.0” encoding=“UTF-8”?>
<ItemError>
<ErrorSet>
<ErrorScreen screenUrl=“http://127.0.0.1:9982/Rhythmyx/psx_cerffImage/rffImage.html?sys_revision=1&sys_contentid=36530&sys_command=preview”/>
<ErrorMessage no-escaping=“yes”>img1: at least one value expected.<br id=“xsplit”></ErrorMessage>
<ErrorFieldSet>
<ErrorField displayName=“Image:” submitName=“img1”/>
</ErrorFieldSet>
</ErrorSet>
</ItemError>. Please consult the log for further information…
The call-stack was:
com.percussion.cms.PSCmsException: Validation error occurred while processing “http://127.0.0.1:9982/Rhythmyx/../psx_cerffImage/rffImage.html?sys_revision=1&sys_contentid=36530&sys_transitionid=15&sys_command=workflow&WFAction=AgetoPublic&sys_workflowid=6”, validation error is: <?xml version=“1.0” encoding=“UTF-8”?>
<ItemError>
<ErrorSet>
<ErrorScreen screenUrl=“http://127.0.0.1:9982/Rhythmyx/psx_cerffImage/rffImage.html?sys_revision=1&sys_contentid=36530&sys_command=preview”/>
<ErrorMessage no-escaping=“yes”>img1: at least one value expected.<br id=“xsplit”></ErrorMessage>
<ErrorFieldSet>
<ErrorField displayName=“Image:” submitName=“img1”/>
</ErrorFieldSet>
</ErrorSet>
</ItemError>
at com.percussion.server.agent.PSAging.checkValidationError(Unknown Source)
at com.percussion.server.agent.PSAging.transitionItem(Unknown Source)
at com.percussion.server.agent.PSAging.run(Unknown Source)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)

Does the img1 field on the content item you’re submitting have any value?