Load dynmaic image into movieclip

I have a movieclip that I would like to load an image into. I can’t even get it to load just a normal image…with, for example: test_mc.loadMovie(“http://www.trpsearchit.com/images/hw3image/hourly_KROC_rochester_ny_us_010066_ffffff_5003544720.png”);
That was just for test purposes, what I really want it to do is process this: “http://www.trpsearchit.com/cgi-bin/weather/trpweather.cgi?forecast=hourly&pands=14626&config=png&alt=hwicc&hwvttf=&daysonly=1&hwvbg=010066&hwvtc=ffffff&hwvusettf=0
I was thinking it would have to be in an IF statement, that when (loaded) then take the URL that it returns and have the movieclip load it. The test link (the first one) is the what the server processes when you type in the second link in your browser…
I was messing around with it for a few hours with no luck, can anyone help?

Thanks!!
-TJ