Array Formula VIa VBA Applied to Blank Cells GIving Error - arrays

Question

I have macro that is attempting to check a column to see if there are any blank cells. In any blank cells I need to place an array formula.
The array formula functions fine on sheet and it is:
=INDEX($CJ$1:$CJ$100,MATCH(1,INDEX(($CL$1:$CL$100=CL2)*($CJ$1:$CJ$100<>""),0),0))
In the macro I cannot use fixed ranges so CJ100 and CL100 Need to be CL "LastRow" and CJ "LastRow" as the data ranges are dynamic.
Thus far I have this code:
Dim ws as worksheet
Dim LastRow as long
Dim i As Long
set ws = worksheets("Sheet1")
With ws
LastRow = ws.Range("B" & rows.Count).End(xlUp).Row
For i = 1 To LastRow
If ws.Range("CJ" & i).Value = "" Then
Range("CJ" & i).FormulaArray = "=index(CJ1:CJ ""& LastRow"",MATCH(1,INDEX((CL1:CL ""& LastRow"" = CL ""&i"")*(CJ1:CJ ""& LastRow <>""""),0),0))"
End If
Next i
End With
I am getting an error on this line: Range("CJ" & i).FormulaArray = "=index(CJ1:CJ ""& LastRow"",MATCH(1,INDEX((CL1:CL ""& LastRow"" = CL ""&i"")*(CJ1:CJ ""& LastRow <>""""),0),0))"
The error is the dreaded "Unable to set the FormulaArray property of the Range class".
After doing some research, it appeared that because I am applying to formula to one cell at a time, perhaps I do not need to use .FormulaArray I change the problem line to use .formula = "-=.... but this resulted in a "Application defined or object defined error" message.
Thinking the issue may be with my use of range I tried the following variation:
Dim LastRow as long
Dim ws as worksheet
set ws = worksheets("Sheet1")
LastRow = ws.Range("B" & rows.Count).End(xlUp).Row
Set rng = ws.Range("CJ2:CJ" & LastRow)
For Each cell In rng
'test value in column CJ
If cell.Value = "" Then
'inserts formula
cell.FormulaArray = "=index(CJ1:CJ ""& LastRow"",MATCH(1,INDEX((CL1:CL ""& LastRow"" = CL2)*(CJ1:CJ ""& LastRow <>""""),0),0))"
'cell.arrayformula
End If
Next
End With
This results in the same Formula Array error as my code at the top of the post.
I don't believe the formula is over 250 characters unless I am counting characters incorrectly? Perhaps there is a syntax error somewhere?

Answer 1

Your implementation of Array formula is incorrect and you have also not qualified the range reference correctly as preceding dot is missing.
Range("CJ" & i).FormulaArray = "=index(CJ1:CJ ""& LastRow"",MATCH(1,INDEX((CL1:CL ""& LastRow"" = CL ""&i"")*(CJ1:CJ ""& LastRow <>""""),0),0))"
Here's updated code which should work for you:
Sub ApplyArrayFormula()
Dim ws As Worksheet
Dim LastRow As Long
Dim i As Long
Set ws = Worksheets("Sheet1")
With ws
LastRow = .Range("B" & Rows.Count).End(xlUp).Row
For i = 1 To LastRow
If .Range("CJ" & i).Value = "" Then
.Range("CJ" & i).FormulaArray = "=INDEX($CJ$1:$CJ$" & LastRow & ",MATCH(1,INDEX(($CL$1:$CL$" & LastRow & "=CL" & i & ")*($CJ$1:$CJ$" & LastRow & "<>""""),0),0))"
End If
Next i
End With
End Sub