Purchade Order Number field status FB01 with special indicator

Hi Experts,

Im facing a problem that i wasnt able to fix a solution.

I have the field status set for a set of account, by posting key and by field group, and the customizing defines the Purchase Order number as a optional entry for those set of accounts and the pretended posting keys.

My problem is that when posting on FB01 with a special indicator the Purchase Order number is not displayed, but if i try via f-48 the same field gets displayed..

Can anyone help me on this?

Thanks

Regards