User Exit at the time of saving Prod Order.

Hi All,

I am an ABAPer.I have a requirement where I need to change the format of serial no generation.The new format has to take care of Basic start date in consideration.As of now the serial no is generated through a user exit which has a FM in it.The FM uses current date for generation.Also serial no gets generated when a Prod Order is saved.Now this FM doesn't have any import parameter where i can pass start date i.e field gstrp in CAUFVD.Now i want to know any user exit which gets called on saving Of Prod order so that i can pass start date through that.I have tried PPCO007

and PPCO0012 but they didn't get called on saving of Prod Order.Can someone suggest how to achieve this.

Thanks in Advance,

Saket.