Database item in Fast Formula

[zafarkarachi]

How can is use database item of basic pay element to
calculate hosue rent in House rent element.

I have used the following database item but formula returns house rent element as null.

baisc_pay_pay_value_input_value

Is there any thing i am missing?

can any body send me the procedure.


Thanks

[alruwaished]

The of database item equal the element name and the value name