Nios IDE debugging

Hello,

I have some problems with the Nios IDE and debugging. I want to debug an OS and an application. If I step into the application the Nios IDE debugger find the sources but if i step into an OS function the debugger doesn´t find any sources. If I debug manually with the GDB inside (GDB inside connects to an GDB server interface), the GDB degbugger find the sources. Does anybody know what´s wrong?