With Range .... why not working?

I'm fairly new working with Range variables and various actions. FYI, FindRows and FindCols are private functions that return number of non-empty rows as long and number of non-empty columns as long.

Not sure why this isn't working:

Dim NumberOfRows As Long
Dim NumberOfColumns As Long
NumberOfRows = FindRows("Report", 2, 1)
NumberOfColumns = FindCols("Report", 1, 2)
        
Dim FormatRng1 As Range
Set FormatRng1 = Range(Cells(1, NumberOfColumns), Cells(NumberOfRows, NumberOfColumns))

With Sheets("Report").Range(FormatRng1).Borders(xlEdgeLeft)
   .LineStyle = xlContinuous
   .ColorIndex = xlAutomatic
   .TintAndShade = 0
   .Weight = xlThin
End With