The following module was built either with optimizations enabled or without debug information

When you find this bug, follow the following steps in sequence:

1>Go to bin folder of you project and remove the dll where you find above error.
2> Browse the project and right click on bin folder and uncheck readonly checkbox. Click OK.
3> Right click on project and click on add reference option. Add the existing project as dependency project.
4> Build web service and test it.

It will resolve your problem. If you find more help send me reply he in comments.

Regards,
Vijay Modi