Script component set get / ProcessDataValue

Inside the script cmponent how can I set and get the process data
which is either Object or custom Object?

I found some info at on these methods
patExecContext.setProcessDataValue(aPath, aVal)(aPath, aVal)patExecContext.getProcessDataValue(aPath)
at http://kb.adobe.com/selfservice/viewContent.do?externalId=kb402587
but it is not working as mentioned but getting error (see below) any clue why?

Thanks
Yog

Target exception: ALC-DSC-119-000: com.adobe.idp.dsc.util.InvalidCoercionException: Cannot coerce object: