Safari Web Inspector not able to set break point in dynamically loading js file

I am running into an issue where I would like to set break points in a dynamically loaded js file using safari 7.0.6. This file is not listed as a resource in the web inspector but is listed as a XMLHttpRequest(XHR). However after dynamically loading the js file, I am unable to insert a break point in that file. Any suggestions will be greatly appreciated.