Run Time Error 13 Passing Cell Value To Variable

I am having a problem with a run time 13 error on a variable assignment. The variable is being assigned a value from a cell that contains a formula, and I am suspicous that perhaps the mismatch is coming thru this. The de-bugger stops on:

Area = ActiveSheet.Cells(count + 41, 8). Here is the complete code (with all my poor coding skills!)

Sub Reservoir()
Dim Inflow As Single
Dim Withdrawal As Single
Dim Evap As Single
Dim Area As Single
Dim Spill As Single
Dim Stor_1 As Single
Dim Stor_2 As Single
Dim count As Integer
Dim max As Integer
max = ActiveSheet.Cells(9, 4)
For count = 1 To max * 12
Stor_1 = ActiveSheet.Cells(count + 40, 11)
Inflow = ActiveSheet.Cells(count + 41, 4)
Withdrawal = ActiveSheet.Cells(count + 41, 6)..........................