I create a function called BassDiff1()
I put it in General/Standard module:VBAProject\Modules\Module1
I an trying to use it in a worsheet formula: example: =BassDiff1(L37)
It works fine except when I start working on another workbook and come back,
it displays #VALUE!
this is the function:
Any help greatly appreciated
thanks

Option Explicit
Public NDataPoints As Integer
Dim Vara, Varb, Varc As Long
Public InputDataCell1, SummaryOutput, YVar As Range

Function BassDiff1(num)

'VARIABLES
Dim m1 As Variant
Dim p1 As Variant
Dim q1 As Variant

NDataPoints = Range("NDataPoints").Value
Set YVar = Range(Range("YVarCell1"), Range("YVarCell1").Offset(NDataPoints -
1, 0))
Vara = Range("Vara").Value
Varb = Range("Varb").Value
Varc = Range("Varc").Value

m1 = Application.WorksheetFunction.Sum(YVar)
p1 = Varc / m1
q1 = p1 + Vara

'FUNCTION
BassDiff1 = p1 * (m1 - num) + (q1 * (num / m1) * (m1 - num))

End Function


--
caroline