I didn't realize that you were using older dbfs. Then you will need to manually set your primary key for the update. There is a property called PrimaryKey in the DataTable class. You will need to set this to the DataColumn that contains the unique key. Here is some sample code:

DataColumn[] myColArray = new DataColumn[1];
myColArray[0] = myTable.Columns["CustID"];
myTable.PrimaryKey = myColArray;

>Nope, Thats what I've been trying to stress. This is a foxpro dbf from the DOS days, Not A VFP DBF. The DBF has a CDX for unique collating sequences, but I dont see anyway in donet to specify which one is primary. I need to leave the dbf's alone tell dotnet which TAG in the index is the primary.
>
>Try making a database with only UNIQ indexes and you'll see the issue. You could also "COPY TO tablename TYPE FOX2X" to build it in the older format.
>
>Thanks Again,
>Mike