Could not load assembly error

Question

Hello friends, I am new to VS 2005 and asp.net 2.0. I make one website in asp.net 2.0 . I publish the site locally and  upload it to the web server.The site is running locally, but when uploaded to the server, it gives error such as "Could not load file or assembly. App_Web_ ****", What is reason behind this? and how to resolve it? Please help me