Need help on UDT Fast Formula in EBS

Hi Experts,

we have requirement like based on the location we need to deduct some amount.So I have created the User defined table(UDT) for location and enter the location with value and also created the fast formula as below but it's returning the null value.please help me on this where i am missing.

Default for ASG_LOCATION is  ' '

l_location=ASG_LOCATION

l_amount=to_num(GET_TABLE_VALUE('LOC_UDT','Location',l_location))

return l_amount

LOC_UDT----Table Name

Location---Column Name

Thanks,

Nagaraju.