Trouble using 'Is Not Nothing'

I have a spreadsheet I'm trying to automate (I find that once people find out you can do that type of thing, they have more for you to do ). I have the code below. When I run the code, it returns a 'Compile Error: Invalid Use of Argument' and highlights the 'Is Not Nothing' portion of my conditional statement. I asked google what it thought about this, but it wasn't giving me much that was helpful.

I would be grateful if someone could point in the direction of an answer to this problem. Thank you.

Here's the code...

Sub EverGreenPastures()
'******* Put "Look Here" anywhere there are line names. *******'
'first import all line names in the spreadsheet to an array for comparison.
Sheets("Info").Select
Dim LineNameArray(1 To 6) As String
RowCountForLineNames = Range("A6000").End(xlUp).Row
For i = 1 To RowCountForLineNames
    LineNameArray(i) = Range("A" & i).Value
Next i

'Put "Look Here" where needed.
Sheets("AdHoc Report").Select
Dim RowCount As Integer
RowCount = Range("A50000").End(xlUp).Row
For j = 1 To RowCount
    CurrentLineName = Range("A" & j).Value
    For k = 1 To UBound(LineNameArray)
    If CurrentLineName = LineNameArray(k) And CurrentLineName Is Not Nothing Then
        Range("Z" & j).Value = "Look Here"
    End If
    Next k
Next j
End Sub