Unable to get countif property of the worksheet function class

I keep getting the following error, when I run my macro:

Runtime error '1004'
Unable to get countif property of the worksheetfunction class

Sub LinkList()
    Dim SearchRange As Range
    Dim FoundCells As Range
    Dim FoundCell As Range
    Dim CompareLikeString As String
    Dim SearchOrder As XlSearchOrder
    Dim MatchCase As Boolean
    Dim OutRng As Range
    Dim Orisht As Worksheet
    Dim stringform As String
    Dim stringform2 As String
    Dim sform3 As String
    Dim rscut As String
    Dim Rsf As String


Set Orisht = Worksheets("LinkList")
Set OutRng = Orisht.Range("A65536")

    For Each Worksheet In Worksheets
        With Worksheet
        Select Case Worksheet.Name
        
        Case "LinkList"
        GoTo nxtwks
             
        End Select
        End With
    
'search in this range in search worksheet
    Set SearchRange = Worksheet.Range("A1:BM3000")
    CompareLikeString = "*[[]*[]]*"
    SearchOrder = xlByRows
    MatchCase = True
    
'find matching cells
    Set FoundCells = WildCardMatchCells(SearchRange:=SearchRange, CompareLikeString:=CompareLikeString, _
        SearchOrder:=SearchOrder, MatchCase:=MatchCase)

    If FoundCells Is Nothing Then
        'MsgBox "No cells in this worksheet" --Not in use
    Else
        For Each FoundCell In FoundCells
            
stringform = FoundCell.Formula



'trim stringform of cell references
    For x = 1 To 6
    Rsf = Right(stringform, x)
    rscut = Left(Rsf, 1)
    If rscut <> "!" Then GoTo Nxt:
    stringform2 = (Left(stringform, Len(stringform) - (x + 1)))
Nxt:
    Next x

 'time off the  = so not recorded as a formula
 sform3 = Right(stringform2, Len(stringform2) - 2)

'if the link has already been listed dont record again 
If Application.WorksheetFunction.CountIf(Worksheets("LinkList").Range("A1:A65536"), sform3) > 0 Then GoTo skip
            
        OutRng.End(xlUp).Offset(1, 0).Value = _
        sform3
            
skip:
        Next FoundCell
    End If
    
nxtwks:
 Next Worksheet

End Sub

The macro searches all sheets for external links, and records unique entries the linklist worksheet. (original function from an online example I cant recall where).

It works great where there is only 1 link in a cell. However it trips up when there are for instance link+link in the cell formula. It dies at the countif line with the above error.

Does anyone have any idea why? While I'd prefer to leave the countif line in to remove duplicate entries, there wont be too many of these types of values in the workbooks anyway, so I tried to have it just skip the 'check if already listed' part if this error occured and just add the link to the list anyway (to be sorted out manually later) but i cant seem to make an error handler that works either.

Ideas experts?!