Can somebody help to solve this problem

Hello,everyone.When I use “newservicethread” to generate a sery of forty thread to do some SQL Server selecting and inserting and updating tasks,The WM6.15 Developer always appears error message like:“Connection is busy with results for another hstmt”,and I use WMDB settings.My question is : When use multi-thread to invoke the same one service to manipulate the same one DB(such as selecting and inserting operations),it will always be failed?
thanks for your help.