Merge DataSets

Hi, How do I merge two datasets?

I've tried the merge method but what happens is that it duplicates the records instead of overwriting the values. I've defined a primary key and it still doesn't work :-(

My intention is to merge two datasets with the same structure and then do a GetChanges(DataRowState.Added | DataRowState.Modified | DataRowState.Deleted).

What am I missing?? Can anyone help me?

I've also tried to implement diffgrams following the article in this link: http://www.vbdotnetheaven.com/UploadFile/mahesh/GetChancesofDataSet04252005060431AM/GetChancesofDataSet.aspx

But again it doesn't work.

Regards,

PF