[rtems] multitasking problem

[Stan]

On my board, the sample apllication 'hello word' running well.
But the 'clock tick' application not executing properly ;)

rtems_task_create and rtems_task_start return RTEMS_SUCCESS
but in rtems_task_delete, the User_extensions_thread_begin abort.

The workspace size and program heap size appears well.

How to find origin this problem ?
any idea ?

Thanks a lot.

BSP: custom, based upon efi68k

Stan.