IF statements not outputting proper value - excel

Question

So I have been trying to automate a process in excel with vba and I seem to be having trouble. I haven't done a lot with vba before and I appreciate any help. I have asked a couple questions before and looked up info on google and here, but my program still isn't running properly.
If I run this code just once then it works perfectly fine, but I want to run it 30 times with results continually updating and putting the new answer into a different cell then it doesn't work. Basically returns the correct answer for the first run but every time after that it generates the wrong response.
So below is my code, any help with this would be greatly appreciated!!!
For i = 19 To 19
Range("AA3:AA7").Select
Selection.ClearContents
If Cells(i, 26) > 499999 Then
Cells(3, 27) = 499999
ElseIf Cells(i, 26) < 499999 Then
Cells(3, 27) = Cells(i, 26)
End If
If Cells(3, 27) < 499999 Then
Cells(5, 27) = 0
ElseIf Cells(i, 26) > 999999 Then
Cells(4, 27) = 500000
ElseIf Cells(i, 26) < 999999 Then
Cells(4, 27) = Cells(i, 26) - 499999
End If
If Cells(4, 27) = 0 Then
Cells(5, 27) = 0
ElseIf Cells(i, 26) > 1999999 Then
Cells(5, 27) = 1000000
ElseIf Cells(i, 26) < 1999999 Then
Cells(5, 27) = Cells(i, 26) - 999999
End If
If Cells(5, 27) = 0 Then
Cells(6, 27) = 0
ElseIf Cells(i, 26) > 4999999 Then
Cells(6, 27) = 3000000
ElseIf Cells(i, 26) < 4999999 Then
Cells(6, 27) = Cells(i, 26) - 1999999
End If
If Cells(6, 27) = 0 Then
Cells(7, 27) = 0
ElseIf Cells(6, 27) = 3000000 Then
Cells(7, 27) = Cells(3, i) - 4999999
End If
Cells(i, 30).Value = (Cells(3, 28) + Cells(4, 28) + Cells(5, 28) + Cells(6, 28) + Cells(7, 28)) / Cells(i, 26)
Next i

Answer 1

You haven't got anything in place for when the value is exactly the figure eg <499999 and >499999 doesn't account for =499999.
You also don't need to state next i - just a next will do.
I'm not sure why you're updating a cell then adding them together, you'd be better off assigning the cell values to variables as with the below. If you'd like to see where it is going wrong I may be an idea to add msgbox calls to show the values as it iterates:
Dim I as integer
Dim value1, value2, value3, value4, value5 as integer
For i = 19 To 49
If Cells(i, 26) > 499999 Then
Value1=499999
Else
Value1=Cells(i, 26)
End If
' and so on...
Cells(i, 30).Value = value1+value2 etc...
Next