How the version of PRJPCB file is 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.