I have a spreadsheet with a date in cell S5

I want the macro to look down cells S10:S300 and see if the date in S5 is in
any of the columns in S10-A300. If it is I want the found row to be deleted.

I have used this code but it is not working and keeps saying nothing is found.

Dim FindString As String
Dim rng As Range


FindString = Range("s5").Value

If FindString < "" Then
With Sheets("Sheet1").Range("s9:s500")
Set rng = .Find(What:=FindString, _
After:=.Cells(1, 1), _
LookIn:=xlValues, _
LookAt:=xlWhole, _
SearchOrder:=xlByRows, _
SearchDirection:=xlNext, _
MatchCase:=False)
If Not rng Is Nothing Then
Application.Goto rng, True
Else
MsgBox "Nothing found"
End If
End With
End If

Can anyone help? Many thanks.