Room Tag is not in a properly enclosed region.

[daniel.hurtubise70031]

Any way to find out where ? It seems to me that its well closed.

[sbrown]

The easiest way for me is to place a room separation line around suspect areas, when it closes, then I know I've isolated the problem area.

[Steve_Stafford]

...place a room separation line around suspect areas...and/or put a separation line down the middle of a space, dividing into two rooms. Move the tag to one side, if it reports area...you know which side to focus on. Move or sketch a new separation line(s) closer to the problem side to "squeeze" the problem.

Common culprits...

curtain wall and wall intersections
multiple wall intersections, particularly where columns occur
Embedded walls and intersections
Revit is pretty forgiving about room areas...then again sometimes, no...see attached images.

[daniel.hurtubise70031]

Tried your trick, couldnt get it to work
I attached the floor

[Steve_Stafford]

Tried your trick, couldnt get it to work
I attached the floorFor some reason all the walls have their room bounding option unchecked. Select all the walls, then view the properties of the walls...scroll down and check the Room Bounding option.

[daniel.hurtubise70031]

Damn, i didnt even checked that, sorry for wasting your time.
But thanks a lot anyway :-)