register DLL in ASP.NET

I'm getting

Error Type: Server object, ASP 0177 (0x800401F3) Invalid class string /ErrorProcess.asp, line 64

error while I try to run my project in ASP.NET. I've registered all the necessary DLLs but it is not working.

Do I have to restart my machine after registration? or is there any other problem?

In the asp.net you need not to register dll. You can add reference of dll and use it. Right click on asp.net project and click on "Add Reference" and add the dll reference. Then you can use it.