Error handling within a Do Loop

[Boondoggler]

I'm comparing two list of numbers on two different sheets to see which numbers have been omitted from one of the lists. I'm trying to use a Find statement with error trapping within a Do Loop to capture the missing numbers within a text string. The code works fine for detecting and capturing the first missing number, but when the second error occurs I just get the "Object variable or With block variable not set (Error 91)" error message. Is there something I have to do to "reset" the error handling? I tried err.clear but that doesn't seem to work. My code is below...

Sub EDTankNoCompare()
Dim TankNo As String
Dim EDTankList As String
Dim counter1 As Integer
Dim counter2 As Integer
TankList = ""
Sheets("End Day").Select
Range("A6").Select
Do Until ActiveCell.Value = ""
    Do Until ActiveCell.Value = ""
        TankNo = ActiveCell.Text
        Sheets("Start Day").Select
        Columns("A:A").Select
        On Error GoTo ErrorHandler
        Selection.Find(What:=TankNo, After:=ActiveCell, LookIn:=xlFormulas, LookAt _
            :=xlWhole, SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:= _
            False, SearchFormat:=False).Activate
        Sheets("End Day").Select
        ActiveCell.Offset(1, 0).Select
    Loop
    Exit Sub
ErrorHandler:
    Select Case Err.Number
        Case 91
            Sheets("End Day").Select
            TankList = EDTankList & ActiveCell.Text & ", "
            ActiveCell.Offset(1, 0).Select
            Err.Clear
        Case Else
            Resume
    End Select
Loop
End Sub

[Sa DQ]

Option Explicit
Sub ComperingColumnsInSheets()
 Dim Sh As Worksheet, Rng As Range, sRng As Range, Cls As Range
 
 Set Sh = ThisWorkbook.Worksheets("End Day")     '<=|'
 Set Rng = Sh.Range(Sh.[a6], Sh.[a6].End(xlDown))
 Sheets("Start Day").Select
 For Each Cls In Range([a2], [a2].End(xlDown))     '<=|'
    Set sRng = Rng.Find(Cls.Value, , xlFormulas, xlWhole)
    If sRng Is Nothing Then
        Cls.Offset(, 4).Value = "Nothing"
    Else
        Cls.Offset(, 4).Value = "Row: " & sRng.Row
    End If
 Next Cls
End Sub