Search a string for a specific text value from cells

Sorry, its in VBA so here is what I've come up with:

Set CBws = Worksheets("Sheet1")
Dim testvalue As String



For i = 3 To 143
testvalue = Worksheets("Sheet1").Range("A" + i).Value

  If InStr(1, testvalue, ConnectorNum, vbTextCompare) = True Then
    MsgBox "Insert Found"
    Else
    MsgBox "Insert not found"
  End If
  
Next i

ConnectorNum is a string that I am searching in. It is defined earlier. This above code doesn't work however, I get type mismatch on the testvalue line..