Hi Hardik, when you upload a bpmn2 process into guvnor (let's say from your eclipse environment) most of the time the package definition in your process is not "defaultPackage". In order for a process to build in Guvnor, the process "packageName" attribute has to be set to the name of the Guvnor package it is contained in. Here is an example:
...
<process processType="Private" isExecutable="true" id="myProcess" name="My Process" tns:packageName="com.sample" >
...
if you place this process in the Guvnor defaultPackage, you would need to change tns:packageName="defaultPackage".
Hope this helps.