SRM7 - Account Assignment Type

Hi,

We are finding the account assignment type field to be a bit problematic when creating the PO. First it defaults to "Unknown", even when we select cost centre. There is no default set in PPOMA_BBP,

We have to select it twice, then sometimes we cannot edit it at all and other times if we delete a line it still checks the value.

Anybody else experience this? I notice each time its changed it seems to run the CHANGE badi, can we disable this.

Thanks

Tony