Reflection not work from third party library [on hold]

I have an application, which use reflection to search for example: annotations in Classes in a given .jar-File. On the main-Method of the application it works fine (say it prints 2 found annotations). But if I add this application as third party .jar library to another application for examplen in vaadin-application it does not works. It prints 0 found annotations.

Can someone help me please?