Can't access website outside local when doing .webtests

Alright I'm trying to set up .webtest for doing load/stress tests at our company and it can do all the company's local DEV/QA test servers just fine... but they try accessing outside resources / websites and they don't work/fail.... I can't seem to figure out why they don't work so i just delete those lines, but that won't simulate real load tests if they fail to load everything and are unable to simulate real world access of our websites.