All I can suggest is to read the section in the help menu or manual on OMF files. I have no experience with them.
For example:
A few general guidelines for preparing files for import into SONAR:
● version 2 is preferred.
● AIFC can take slightly longer to open, as the data must be converted to WAVE on read, so WAVE is the best choice.
● If exporting from Avid Xpress DV, select "embed" (not "link") when exporting the file, and don't include any video.