Problem with Preview not mailing files

Last weekend I upgraded my brand new iMac 27" computer from Snow Leopard (which was installed when it was delivered) to Lion. There is one problem I have not been able to solve. When using Preview, there is an option to "Mail selected PDF document" (or 'image' in the case of a jpg file etc). I used this feature all the time in Snow Leopard. When I click on it, I get an error message saying, "Import Failed. Couldn't import the selected images into Mail". I have repaired permissions, removed the preference file and Googled the problem all to no avail. Is this a bug in Lion as it worked perfectly with Snow Leopard? I have tried mailing from other apps like iPhoto and there are no problems with them at all. Any help would be gratefully received. Thanks.