Hello.  
I'm using Excel X (VBA5) and trying write a macro which will change the
interior cell color of those cells whose value is in the top ten percent of
the selected range of cells. I was able to do this quite easily with
conditional formatting using the percentile formula, but I want to be able to
do it with a macro and explicit formatting. The below macro returns a "sub or
function not defined" error when it gets to PERCENTILE:

Sub NLFI_TopTenPercent()
'
' having selected the cells before running,
' first create range from selection
'
   Selection.Name = "TopTenPercent_Range"
'
' add Loop to check each cell in range
'
   For Each Cell In Range("TopTenPercent_Range")
'
' check Cell value against values in Range
' shade cell Yellow if > or =
'
       If (Cell.Value >= Percentile("TopTenPercent_Range", 0.9)) Then
           Cell.Interior.Color = vbYellow
       End If
   Next Cell
End Sub

Maybe I need a dim statement at the top?  
And and all help would be appreciated.