How the versions of ECAD files are maintained in EPDM ?

Is there any relationship maintained in EPDM for PRJPCB with its contents ?

Files which are related to PRJPCB file is not updating in EPDM vault if I change the version of PRJPCB file.

Some files in PRJPCB files contains no data when changing the version of the PRJPCB file using EPDM. In this situation how we have to handle the data while version migration?.

Thanks in Advance!!!