Hello to all,
finally I found a bug into my code which is not related with join functions. Now all works fine. Thank you for support (and tolerate) me!

I have one just one last question (another!) to you:
I create a pthread with joinable attribute, and then I transform it in a realtime ask with rt_task_shadow().
When I join this task I must call pthread_join(), because rt_task_join() generates a segmentation fault (in the point where latter function internally calls pthread_join()).
Is this behaviour correct?

Thanks again in advance, regards
Mauro