As described in Issue #1002 if you have a link in this situation:
<a href="abc"> <img src.../> </a>
then you will not decorate the link correctly and cross domain linking will not work.
This is now resolved in v3.1.4 (thanks to @philipherrmann), so it is recommended to upgrade to v3.1.4 if using crossDomainLinker in your tracker options. This issue does not effect any v2 releases.