ABAP GUYS worked on FI/CO module report (urgent)

hi i am creating a vendor ageing report.

in that i have to calculate the ageing

which is nothing but

AGEING = Current date - BLINe Dt(ITAB-ZFBDT)

data:ageing type i.

i have used fm date_between_two_days

but couldn't achieve the result.

so if any one has solution then plz share with me.