Do...Loop failure!

Ok, I thought I was being smart and have produced the following code:

Sub total()

Sheets("Summary Sheet").Select
Range("c3").Select
m = 0
n = 0
o = 0
p = 0
mins = 0

Do While ActiveCell.Offset(m, n) <> ""
    Do While ActiveCell.Offset(m, n) <> ""
        Sheets("Summary Sheet").Select
        Range("c3").Select
        mins = mins + ActiveCell.Offset(m, n).Value
        m = m + 4
    Loop

    Sheets("Tables").Select
    Range("b3").Select
    ActiveCell.Offset(o, p).Value = mins
    mins = 0
    o = o + 1
    m = 1
    If o = 2 Then
        o = 0
        m = 0
        n = n + 1
        p = p + 1
        Sheets("Summary Sheet").Select
        Range("c3").Select
    Else
        Sheets("Summary Sheet").Select
        Range("c3").Select
Loop

End Sub

But it's kicking out a loop failure, because it says it can't have a loop without a 'Do'. However, I have 2 'Do's and 2 'Loop's so I don't see why it's not working.

The code is supposed to add up the values in (n) number of rows (each 4 rows apart) and paste that value into a cell on a different sheet, then repeat, offset down one row, then repeat on the original row series but offset one across... etc and so on, until it runs out of values to add and paste.

Any help would be much appreciated...

fd.