violation unique key constraint [solved]

[Techno]

yes - this is a wierd one which i havent encountered before. when the tableadapter's update command is called I get this error.

"System.Data.SqlClient.SqlException: Violation of UNIQUE KEY constraint 'IX_ReportColumn'. Cannot insert duplicate key in object 'ReportColumn'.
The statement has been terminated.
   at System.Data.Common.DbDataAdapter.UpdatedRowStatusErrors(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount)
   at System.Data.Common.DbDataAdapter.UpdatedRowStatus(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount)
   at System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping tableMapping)
   at System.Data.Common.DbDataAdapter.UpdateFromDataTable(DataTable dataTable, DataTableMapping tableMapping)
   at System.Data.Common.DbDataAdapter.Update(DataTable dataTable)
   at ReportDataSetTableAdapters.ReportColumnTableAdapter.Update(ReportColumnDataTable dataTable) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\website\c7de1566\f50d71c3\App_Code.qbpf4itd.1.cs:line 4112
   at _Default.btnSave_Click(Object sender, EventArgs e) in C:\Projects\BE WebReporting\Website\Default.aspx.vb:line 525"

the table itself has a PK and an FK and has a unique constraint of 2 fields. but its calling the update command so I dont quite understand why its performing an insert statement? perhaps its not.... but why would there be duplicate keys being inserted?