Why can't I see this element??!

Arggh, there is nothing worse than trying to find why an element isn't visible in a view, so many different potential causes that need to be checked.  I thought I'd put a little bit of a checklist together:

1. Is the view "Discipline" set correctly?  For example if your view is accidentally or purposelly set to Structural the wall may not be showing because its non-bearing...
2. Is the view range set correctly to see the particular element?  I'll often switch to my 3D view and orientate it to match the view, if I can't see it in the 3D view its most likely a view range issue.
3. Is the element in the correct phase and is an appropriate phase filter set in the view to make it visible.  Maybe someone set it in a future phase?
4. Can you see the element by enabling "Reveal Hidden Elements"?  If so, select it and select unhide element or unhide category.  Try not to use the Override element or hide in view options...
5. Is the element in a worset that isn't open or turned on in the view?
6. Is there a filter applied to the view that is causing the element to be hidden?
7. Has someone used the linework tool on the element?
8. If its a family, is the detail level of the view set correctly?  Sometimes families are set not to show at Coarse.
9. If its a family, has someone selected the geometry of the element not to show in plan, section/elevation as the case maybe?
10. Maybe the view has been created as a detail view?  By default certain categories aren't visible in a detail view...  As such change to a standard section.
11. Is the element part of a design option and perhaps that isn't the current option for that particular view?
12. Is there a plan region in the view that is adjust the view range settings incorrectly for the area in question?
13. If its a datum, is the 3d extents of the datum intersecting the view?
14. If its a section/elevation marker, check the "hide at scales coarser than" parameter to ensure its set appropriately to show.
15. Is it part of a linked revit or dwg file?  Ensure that the link is loaded...

I think there are a few more, but that's all i can think of off the top of my head.  Feel free to post comments of any additional ones you think of and I'll add them.

Cheers!

I know this can do my head in sometimes!