dropdownlist in gridview update error

Question

Hello!

I have a DropDownList nested in GridView. The dropdownlist contains a list of Types of clients the datatextfield is the name and the value field is the ClientTypeID. The GridView is binded with SqlDataSource, which has update statement, but when I try to update one row I get the following error: Incorrect syntax near 'nvarchar'. I don't have any parameters of the type nvarchar. I can't find out what I'm doing wrong and the row can't get updated.

Any suggestions?

10x in advance