Excel Debugging Issue

Hi Here is my code. It's my first day using excel's VBA tool, and I'm getting a mismatch error on the bolded line. Here is my data set.
Screen Shot 2016-06-27 at 1.06.55 PM.png

Sub Button1_Click()
Dim i As Integer
For i = 1 To 3741
    Dim count As Integer
    count = 0
    Dim j As Integer
    j = 0
    Do While Cells(i, 3).Value <> 1
        If Cells(i, 4).Value <> " " Then
         j = j + Cells(i, 4).Value
        End If
        count = count + 1
        i = i + 1
  Loop
 j = j / count
Cells(i, 6).Value = j
Next i
End Sub