Change On-Click Error Message

I have set up a workbook with a number of sheets that requires entries to be made via command buttons on a specific sheet. I do not want the user to be able to change data in the sheets without using the command buttons. I have therefore protected the relevant sheets (locked). When the user tries to input data in a locked cell the usual "this cell is protected......." message appears as one would expect. However, I want to display a more useful message that directs the user to the sheet with the command buttons. Can anyone help me with the VBA code to do this?

Apparently not as per these resources (that include a workaround) :

http://www.xtremevbtalk.com/excel/22...d-message.html

http://www.2013.net/blog/index.php?/...n_excel_sheet/

I should place the warning on the top of each sheet, with text "To edit this sheet, go on the sheet '... name ...'" Users are not stupid (at least some of them) and they learn soon what to do.

(As far as I know myself, I'd extend the warning text into

To edit this sheet, go on the sheet '... name ...'
Here you can edit directly the light-blue cells only.

with no light-blue cells in the sheet, of course )

Thanks for the responses - I will give it a try tomorrow and let you know the outcome.