Need simple look up or match formula

Function ConcatIf(ByVal compareRange As Range, ByVal xCriteria As Variant, Optional ByVal stringsRange As Range, _
                            Optional Delimiter As String, Optional NoDuplicates As Boolean) As String
Dim i As Long, j As Long
With compareRange.Parent
Set compareRange = Application.Intersect(compareRange, Range(.UsedRange, .Range("a1")))
 End With
If compareRange Is Nothing Then Exit Function
If stringsRange Is Nothing Then Set stringsRange = compareRange
Set stringsRange = compareRange.Offset(stringsRange.Row - compareRange.Row, _
                                            stringsRange.Column - compareRange.Column)
For i = 1 To compareRange.Rows.Count
    For j = 1 To compareRange.Columns.Count
        If (Application.CountIf(compareRange.Cells(i, j), xCriteria) = 1) Then
            If InStr(ConcatIf, Delimiter & CStr(stringsRange.Cells(i, j))) <> 0 Imp Not (NoDuplicates) Then
                ConcatIf = ConcatIf & Delimiter & CStr(stringsRange.Cells(i, j))
            End If
        End If
    Next j
Next i
ConcatIf = Mid(ConcatIf, Len(Delimiter) + 1)
End Function