User Defined Function giving #VALUE! error

Hi, I'm hoping you can help.

I've entered a function, but when I try to use it in a cell it just shows the value error. Please find the code below:

Function VLOOKUPINTER(Value, TableArray, ColumnNumber, Interpolation)
.
.
.
VLOOKUPINTER = (ThisY * (NextX - Value) + NextY * (Value - ThisX)) / (NextX - ThisX)

In a cell, I write it as =VLOOKUPINTER(C45,CROWDINGRATIO,2) where CROWDINGRATIO is a named range. I've tried just highlighting a range, but the same thing happens.

I've also tried just using it as a vlookup e.g.

VLOOKUPINTER = WorksheetFunction.VLookup(Value, TableArray, ColumnNumber)

or even just VLOOKUPINTER=3, but it keeps showing the same error.

Could someone please let me know if there's any options I need to activate or whether I've just been silly and missed something obvious.

Many thanks,

T

Hi

What are the other variables? And how are they filled?

rylo