From your query it seesm you want to supply the customer ID. In this case you need to check the number sequence attached with customer Id field and change it to MANUAL from CONTINUOUS.
Faisal, this thread is about a problem caused by continues number sequences. If it’s your problem too, simply go and use the solution described above.
If you have a different problem, you’re off-topic here. Create a new thread for your specific problem and don’t forget to provide much more information.“Is not working” isn’t sufficient definition of any problem.