Updateable Query

Jeg får følgende fejl - når jeg kører mit kode:

System.Exception: Kaos base failed: System.Data.OleDb.OleDbException: Operation must use an updateable query.
  at System.Data.OleDb.OleDbCommand.ExecuteCommandTextErrorHandling(Int32 hr)
  at System.Data.OleDb.OleDbCommand.ExecuteCommandTextForSingleResult(tagDBPARAMS dbParams, Object& executeResult)
  at System.Data.OleDb.OleDbCommand.ExecuteCommandText(Object& executeResult)
  at System.Data.OleDb.OleDbCommand.ExecuteCommand(CommandBehavior behavior, Object& executeResult)
  at System.Data.OleDb.OleDbCommand.ExecuteReaderInternal(CommandBehavior behavior, String method)
  at System.Data.OleDb.OleDbCommand.ExecuteNonQuery()
  at Kaos_Service.ReserveringService.InsertReservering(String dato, String type, Int32 antalP) in c:\inetpub\wwwroot\kaos\kaos_service\reserveringservice.asmx.cs:line 69 ---> System.Data.OleDb.OleDbException: Operation must use an updateable query.
  at System.Data.OleDb.OleDbCommand.ExecuteCommandTextErrorHandling(Int32 hr)
  at System.Data.OleDb.OleDbCommand.ExecuteCommandTextForSingleResult(tagDBPARAMS dbParams, Object& executeResult)
  at System.Data.OleDb.OleDbCommand.ExecuteCommandText(Object& executeResult)
  at System.Data.OleDb.OleDbCommand.ExecuteCommand(CommandBehavior behavior, Object& executeResult)
  at System.Data.OleDb.OleDbCommand.ExecuteReaderInternal(CommandBehavior behavior, String method)
  at System.Data.OleDb.OleDbCommand.ExecuteNonQuery()
  at Kaos_Service.ReserveringService.InsertReservering(String dato, String type, Int32 antalP) in c:\inetpub\wwwroot\kaos\kaos_service\reserveringservice.asmx.cs:line 69
  --- End of inner exception stack trace ---
  at Kaos_Service.ReserveringService.InsertReservering(String dato, String type, Int32 antalP) in c:\inetpub\wwwroot\kaos\kaos_service\reserveringservice.asmx.cs:line 82


Og min kode ser sådan her ud:

OleDbConnection dbConn = null;   
int affected;
       
try
{
  dbConn = new OleDbConnection(@"Provider=Microsoft.JET.OLEDB.4.0;Data Source=" + Server.MapPath("/KAOS/Kaos_Service/KAOS_db.mdb"));
               
  dbConn.Open();         
  string sql = "INSERT INTO Reservation (Dato, Aktivitetstype,  AntalPersoner) VALUES ('"+dato+"', '"+type+"', "+antalP+");";
 
  OleDbCommand insert = new OleDbCommand( sql, dbConn );

               
  affected = insert.ExecuteNonQuery();
}
...

Håber der er et klogt hovede som kan hjælpe mig... :-)