Cannot export to OMF (embedded) but ok with ''refer to audio files apart'' ?

I'm exporting many projects to OMF (for reimport into ProTools 9 HD in another studio).
 
Although I had no problem for many of them, doing both the ''embedded audio'' and ''refer to audio externally'' options.
 
However, there is one project for which I am only able to do the ''refer externally'' but cannot do the ''embedded'' option for which I get the message:
 
''Problem exporting OMF - OMFI_ERR: Mob does not exist in this file''
 
I read in an old message that this should be caused by fact that file is bigger than 2GB (which is the case if I look in the folder to which I exported the ''refer to audio externally'' version.)
 
For other projects, I was told to use this option, so can I assume that this project won't be problematic ? 

UPDATE : I am unable to open in ProTools - I am greeted with a ''missing audio files'' message.  Sorry guys if I ask this here, I know it is partly a Pro Tools related issue... yes and no (see above) - I know I have more chances to get reply here...    


Must now add differences I had with this project within SONAR before exporting:

- other projects: all tracks were first ''bounced to clip'' prior to export to OMF. In this case, I have several tracks for which I have not done this, as I wanted to keep visual with copy/paste sections for which I will need to crossfade.

- I bounced to track some of the tracks that were having volume automation (envelopes) and I either deleted the envelope on the original track afterward (just in case I need to go back), *or* simply deleted the track itself and just keep the ''mixed'' one. 

Although I may sound (above) like I've done dozens of OMF, this is not the case : my success (and sole experience referenced above) have been with 4 or 5 other projects...  So for those of you who have done many more, your insights are very appreciated.
 
Rob