I have my vim setup to use omnicomplete with ctags and its all working well. I have set my .ctags to tag struct members and they are in the tag file but omnicomplete just shows
Omni completion (^O^N^P) Pattern not found
when I do something like mystruct. or mystruct-> Everything else offers good completion.
Is there something else I need to enable in vim or omnicomplete or ctags?
Do you mean "omnicppcomplete" instead of "omnicomplete"? If no, then you might want to use omnicppcomplete.
Also, take a look at clang_complete for perfect completion of C/C++/Objective-C code.