Do while Loop, and For next can use together in sheets?

[ping0775]

If Target.Column = 23 Then
Dim counta, r As Long
countt = Sheets("InvoiceDatabase").Cells(Rows.count, "A").End(xlUp).Row
t = 3
Do While t <= countt

invno = Sheet4.Range("b" & t).Value
invno = Format(StrConv(invno, vbUpperCase))
For r = 3 To Sheet19.Range("c10").End(xlUp).Row
For x = 1 To Len(Sheet19.Cells(r, 3))
a = invno.TextLength
If UCase(Mid(Sheet19.Cells(r, 3), x, a)) = invno Then
paid = Format(Sheet19.Cells(r, "F"), "####0.00") 'Paid
End If
Next x
Next r
Sheet4.Range("ai" & t).Value = Sheet4.Range("w" & t).Value
t = t + 1
Loop
End If

Hi above code apply in Sheets('InvoiceDatabase")
the lopp in Do while work fine.
but when i want to extract the value in sheet19 , it doesn't work anymore
For r = 3 To Sheet19.Range("c10").End(xlUp).Row
how to fixed this?

how to create second loop in another sheets to extract the value

 

[Joe4]

Do you actually have a Sheet with the name "Sheet19", or are you trying to reference by sheet index?

If you look in the VBA Project explorer, it will show both the Sheet indexes and names (indexes are first and name is in parentheses):