IDOC_INPUT_ORDERS - Raise an error on exit don't run - Why ?

Hello,

for Idoc traitement I'm using standard MF IDOC_INPUT_ORDERS .

To do some modification I opened an exit ( EXIT_SAPLVEDA_002 ).

Question:

When I raise an error inside this exit, that status message is Error, status = 51 but the document (sales order)

is created !! Why ??