I am trying to use a TextBox value to determine if a row on another
spreadsheet should be visible or not. I have the following:

Private Sub Worksheet_Change(ByVal Target As Range)

If Worksheets("Input Page").TB21.Value = 0 Then
Worksheets("Summary Report").Rows(19).EntireRow.Hidden = True
Else
Worksheets("Summary Report").Rows(19).EntireRow.Hidden = False
End If
End Sub

It works if I manually override the value in the TextBox's linked cell; say
AC49, but will not if I simply change the value in the TextBox itself like I
would like the user to do.

Any suggestions?