Function does not work in a cell. Please Help
 

I have a program that fill Excell 2000 template with data and functions.
Every function works and shows the right result however one user defined
function show only #NAME? instead of result. When I click on the sell the
function =+calculateNasdRegChargePercent(Z4) appears. I click on a red sign
in the middle of the formula bar between 'x' and '=' and the function
evaluates itself into meaningfull number. The argument in cell Z4 is a
function itself that works OK.
Can anybody help me to force the function to evaluate itself without manual
interaction using VBA. I already used Calculate function with partial
success.
Thanks