Due on Base Line Date BSEG-ZFBDT

Hi,

Field Status of the field Base Line Date/Due Date is not appearing for Special GL Postings (Posting Key 29, 39 Spl GL Indicator V) in F-43, F-48 or F-02.

I have Verified in T.Codes: OB41, OB14, OBC4 and OBA7. my payment trasncation fileds are optional e.g. due on, value date etc..

But Why still not appearing due on while posting advance payments. we are using customized document type "Y2" and posting key 39 or 29.

Please advise how can fix this.

Thanks

srinu