Message error on user-exit MV50AFZ1

Hi!

I need to send a message error on user-exit MV50AFZ1 (VL01N), but I can't, because when I use BAPI_DELIVERYPROCESSING_EXEC for create deliveries, it will abort my program.

My program try to create many deliveries together, when occurs a message error, I don't know what order is the problem!!

Thanks,

Tatiana