User Control (Winforms) doesn't display in web page. looks like unloaded image

[Joe]

I created a user control that I need to use in a web page but the control
doesn't display. I added it to my page using:
<object id="testcontrol"
classid="http:TestControl.dll#TestControl.UserControl1">

all I get is a page with a box that looks like an image that didn't load.

This control requires another .dll which I don't know how to make IE
download it so I registered it using gacutil.

 

[Joe]

I tried a simple control and that works fine so my guess is it has something
to do with the other dependency.