VBCS Tables Primary key

Summary:

How can i update table primary key sequence

Content (required):

I have scenario in which user maintaining the version of documents and we are handling it with procedure by providing primary key , it will simply select data and line data behalf of header line relation and insert on table and for primary key we are using max(nvl(id,0))+1 logic , but after doing this thing vbcs is not able to create new record and unique key error , is there any way i can update that primary key sequence or get running sequence and use on my procedure

Version (include the version you are using, if applicable):