VBA Type Mismatch Error when searching for a string in an array

VBA Type Mismatch Error when searching for a string in an array

I am working on a macro that will consolidate two different sources of
order data. The first source will contain old orders as well as some new,
the second source will contain only the old orders and will have
additional data in columns that were updated manually.
My idea for this is to take the order totals from the second source, paste
them in a sheet after the order totals from the first source, and then
search all the order numbers from the new file against the order numbers
from the existing tracker. I have a for loop that is supposed to find the
order numbers from the new file that are not already in the tracker and
then insert a row with that order detail. I am receiving a Type mismatch
error on the if statement that checks if the string exists in the array.
Please take a look at this code:
Dim r As Integer
For r = 1 To 1000
Dim NewOrd As String
NewOrd = Range(Cells(r, 1), Cells(r, 1)).Value
Dim ExistArray As Variant
ExistArray = Range("a1", Range("a1").End(xlUp))
Sheets("Sheet2").Select
If IsEmpty(NewOrd) Then
Exit For
End If
If Not UBound(Filter(ExistArray, NewOrd)) >= 0 And NewOrd <> "" Then
Rows(r).Select
Selection.Copy
Sheets("Sheet3").Select
Rows(r).Select
Selection.Insert Shift:=xlDown
Application.CutCopyMode = False
End If
r = r + 1
Next r
I have tried a few different ways of setting the array, tried adding
option explicit, and tried nesting for loops (not my brightest efficiency
moment). Would greatly appreciate another set of eyes!
Thanks!