Adding Custom Controls to Toolbox in Visual studio

Question

I am trying to add a dll that contains some custom 3rd party controls and some in house user controls and am getting the following error -

The Assembly "MyASsembly.dll" could not be loaded. Check that any dependencies the file requires are installed

I am using Visual Studio 2003 and the 3rd part controls are C1.

What is wrong?

Answer 1

Has the dll worked in the past with anything else? Does the dll come reference other resources that you know of? Where did the dll come from? Is there documentation accompanying it?