which user exit can be use before production order creating?

which user exit can be use before production order creating?

i want to check AFPO data,then show error message before production order creating.

1.i try to use PPCO0001( enhancement when saving the order) to check AFPO data, then show some error message,sap system will generate a abap down error.

2.i try to use PPCO0007(Exit when saving production order),

i can show error message,but i can't check AFPO's data.