Proforma invoice billing status is not changed to 'A' to 'C'

Hi All,

Before posting my issue here i have searched and i couldn't get the right answer.

After generating billing for Proforma invoice for milestone item category, in my sales billing status is not getting changed to Completely processed form 'A' to 'C'.

Can any one have an idea why it is not getting changed billing status FPLT-FKSAF is 'A' to 'C' .

Thanks,

Preddy.