Thanks Eric.

But like you can see on the posted code, both ISR dont't depend on each other, they are independent.

But with changing the interrupt enable Bits, the ISR are serviced like I would them beeing serviced with the posted code.

At this time I really don't have an idea, why the ISR of the ADC stops beeing serviced after the second interrupt of the RTC?? Because till the second interrupt of the RTC everything works fine!!