Warning message based on expression

[Cmath06]

Hello, I am trying to make a virutal column that displays a warning text message if an expression is valid. I currently have a form where I input a serial number. In the virtual column I want the warning message to show up if that serial number has been used/scanned in the last 30 days.

Here is my expression so far but I’m getting an error.

   IF(
   COUNT(
   FILTER(
   "Delivery",
    AND(
           ([SERIAL NUMBER] = [_THISROW].[SERIAL NUMBER]),
           ([SERIAL NUMBER] = [Delivery].[SERIAL NUMBER]),
           (TOTALHOURS(NOW() - [TimeStamp]) < 30 * 24)
            ))
  ) > 0,
  “This serial number was scanned within the past 30 days”,
  ""
 )

The sheet with the Serial Number column is called Delivery. Any Ideas on how to fix it?