Partial budget release Error

hi Experts,

I believe that partial budget release is possible, but i am getting an error it says" Item WBS element NTD-0001060 budget exceeded

Message no. BP603"

it is not allowing me to do the partial release of budget.

in the budget profile followig have been maintained.

availibilty control-

act type 1, usage -0.00

overall -yes

releases -yes

object currency - yes

please advise that do i need to make any changes.

thanks

Prashant