验证码不在asp.net中工作

hey guys, i have downloaded mondor's captcha control, and implemented on localhost, thats working fine, but when i did the same steps and uploaded to the hosting server, i am unabel to get captcha image,i want to know whats the difference between placing dll's in bin folder and adding it as a reference because anyway it will go in bin folder. on localhost i added a reference to that dll and on hosting server i just added the dll in the bin folder, is that the problem, if yes than what could be the solution for this issue...hey guys, i have downloaded mondor's captcha co