problem jump to an external address function

Hi,

I have a problem with a piece of code written in startup_XMC4400.S:
I need to jump to an external init function with a well know address before jump in main, so:
+ ldr r0, =0x0C020200
+ blx r0

ldr r0, =main
blx r0

When I debug step by step (step into) that works but if I press continue to run this code, it fails (VAC0_G3_3_IRQ_Handler crash).

I don't understand why this work step by step and crash in free running.

How can i do to investigate/solve this problem?