Keil port on ADUC7026

Hello, I have a problem when starting the General purpose timer (1) on my ADUC7026, on which i ported FreeRtos. Timer 1 Interrupt service routine are not executed when i am in supervisor mode. The controller even not enter in the IRQ_Handler routine. But all thing work well when l work in user mode. Can you have any explication for that problem? How can l enter in supervisor mode in C code ? Please help me. Best regards. Emeric 

Keil port on ADUC7026

Tasks run in System mode which is expected by the tick ISR.  The tick being in IRQ and manual context switches being in Supervisor mode.  Not sure what would happen if you manually switched to Supervisor mode.  Most likely would not work. Supervisor mode has its own status register – so most likely you will find that interrupts are disabled in supervisor mode status register.