>I am desparately seeking help. My users are jumping all over me.
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>I have this strange problem. When I am in network environment, my invoice details sometimes get clobber up with details from another station. Any idea what is the reason?
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>I am using NEWID() function in TASTRADE to generate my master table primary key (surrogated). In my grid, I set ALLOWADDNEW = .T. and in BeforeRowColumnChange, I replace foreign key with my master key whenever it is empty. The master-detail table is related together in the data environment and in my gird, the LinkMaster, ChildOrder, RelationalExpr and RecordSource are all set properly. I am using private data session and optimistic buffering.
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>It seems that while my master key didn't move, my grid just suddently got fill up with a few rows of data of another master key (I placed the foreign key field into one of the columns). It seems to happen mostly when the other user saves his invoice.

I am going to assume that when you add a detail row to the grid each row has the same Invoice Number. Do the rows that suddenly appear in your grid have the same Invoice Number as the rows that were originally there? If so your NEWID() function is not working properly with respect to assigning Invoice numbers. If the Numbers are different, are you setting a filter on the table to only display those rows whose Invoice Numbers are equal to the one assigned by NEWID()?