There have been a number of reports about flakiness with publishing to Flickr. Some of the reports seem related to LR 4 and perhaps upgrading to Yosemete (OS X 10.10), others for LR 5. You could try the LR 5 free trial to see if that fixes the problem (and then pay for the upgrade to LR 5, or wait an unknown amount of time to upgrade to LR 6, or move to LR CC).
Over the years Adobe has been very slow to respond to issues with publishing to services like Flickr and Facebook and they rarely communicate with customers about specific problems. You try this third-party Flickr plugin. The author has an excellent reputation and, unlike Adobe, he is very responsive. (He helped design the LR publishing-plugin architecture for Adobe.)
thank you so much man. i took the shortcut and just got the third party plug in, works great. thank you again
I took the plug-in route, and it works just fine. Thanks for your help.