Excel 2007 :: Method Delete Of Object Range Failed

I have written a sub with the purpose of finding rows based on a critieria, copying the rows to another worksheet and deleting the original row.

The code:

Code:
Sub MoveToIgangvaerende()
'
' Flytter opgaven til sheetet Igangværende projekter
'
Dim i, j, Index As Integer
Forfra:
For i = -1 To 1000
If Sheets("Pipeline").Cells(3 + i, 20) = "Ja" Or Sheets("Pipeline").Cells(3 + i, 20) = "ja" Then

[Code] ......

I get the error message "Method 'Delete' of object 'Range' failed" at the line "Sheets("Pipeline").Cells(3 + i, 18).EntireRow.Delete".

The sub has previously worked perfectly fine.