Custom text in the cell if the cell is blank

[ABSTRAKTUS]

Hi all!
I have a trouble with my project. There is one column in my workbook, which sometimes must be filled in. But users sometimes ignore (forget) it. I have made a dummy example for you guys. Please have a look. Give me a suggestion how to make users stop ignoring it. More info in the example.
See attached...

[ABSTRAKTUS]

By the way, forgot to mention, it has to be a formula, not VBA code.

[ABSTRAKTUS]

Ooops... Tha sounds too clever for me. Can you explain step by step how to do it or make it in that dummy example. And I will redo it on my actual workbook.
Thanks!

[royUK]

Ooops... Tha sounds too clever for me. Can you explain step by step how to do it or make it in that dummy example. And I will redo it on my actual workbook.
Thanks!

What does?

[royUK]

In K11& drag down

=IF(VLOOKUP($B11,LOOKUP!$E$3:$I$27,5,0)="Y","Fill in data","")

This will be overwritten when entry is made

[ABSTRAKTUS]

Thanks a ton guys!

[Marcol]

A bit late but try this.