Double booking problem for Reservation Program

[alex410]

Hello everyone,
I am looking for some help with the attached MS Excel Spreadsheet (2nd and 3rd picture/attachment). This is a Conference Room Reservation program on MS Excel.

The formula detects double bookings and highlight them in yellow but I would like it show an error message when there is a double booking meaning the cell value is < 0.
Here is the formula used: =1-SUMPRODUCT(('Conference Room Reservation'!$C$2:$C$1000<=F$6)*('Conference Room Reservation'!$B$2:$B$1000=$I$3)*('Conference Room Reservation'!$D$2:$D$1000>=F$6)*('Conference Room Reservation'!$E$2:$E$1000=$C7))

If there is a double booking the prompt should tell the user that a double booking exists and to book at a different time for that room.
I would also like the booking labels to have the user's name.
Please see the first picture below/attached where I put in how the outcome should look.

Can you please help with this. Thank you so much.
-
Alex

=1-SUMPRODUCT(('Conference Room Reservation'!$C$2:$C$1000<=F$6)*('Conference Room Reservation'!$B$2:$B$1000=$I$3)*('Conference Room Reservation'!$D$2:$D$1000>=F$6)*('Conference Room Reservation'!$E$2:$E$1000=$C7))

 

[Fluff]

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Cross posted at: Help needed with Conference Room Reservation (double booking)
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[alex410]

Please note that I posed this same question on Excel Forums: Help needed with Conference Room Reservation (double booking)
Thank you.

 

[alex410]

I solved this issue on my own so this inquiry is no longer required. Thanks.