VBA problems

[jsuden]

I've been trying to create a macro that will do the following: I want
the macro to loop through a bunch of funds and calculate what would
happen if we allocated 5% to the fund. I have about 20 funds I want to
loop through, all start out with a weight of zero. I then chnage the 0%
to 5% for one fund at a time and copy the resulting volatility
(calcualted iwth the new weight) onto a separate spreadsheet called
Summary. C4 links to the new volatility on the AG spreadsheet, but
needs to be copied,pasted each time since the link stays the same but
the value obviuolsy changes as the weight is updated (im also doing
this with returns and betas/correlations, hence the "G4", "O4" and
"S4"). im encountering a few problems--the macro is giving me problems
with the 2 separately named spreadsheets (I get the error Select method
of range class failed). Then I was also havign a problem with the paste
special function. any suggestions? Is this set up completely wrong???

Worksheets("AG").Range("A76").Select
For i = 0 To 20
Do Until i = 20
ActiveCell.Offset(0 + i, 3).Select
ActiveCell.FormulaR1C1 = "5%"
Worksheets("Summary").Range("C4").Select
Selection.Copy
ActiveCell(0 + i, 1).Range("C4").Select
Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone
Worksheets("Summary").Range("G4").Select
Selection.Copy
ActiveCell(0 + i, 1).Range("G4").Select
Selection.PasteSpecial Paste:=xlPasteValues
Worksheets("Summary").Range("O4").Select
Selection.Copy
ActiveCell(0 + i, 1).Range("o4").Select
Selection.PasteSpecial Paste:=xlPasteValue
Worksheets("Summary").Range("S4").Select
Selection.Copy
ActiveCell(0 + i, 1).Range("S4").Select
Selection.PasteSpecial Paste:=xlPasteValue
Worksheets("AG").Range("A76").Select
ActiveCell.Offset(0 + i, 3).Select
ActiveCell.FormulaR1C1 = "0%"
Loop
Next i
End Sub