access is denied to windows assembly

Why you are copying the DLL in system folder.
Copy it in the Bin Folder of your application.

You can also add this using "Add Reference" Option

You need to copy the DLL in the windows folder, then change the access rights for special folder of windows

Check the link
http://www.addictivetips.com/windows-tips/windows-7-access-denied-permission-ownership/

Hope this will help you :-)

When I right click the c:\windows\assembly folder I don't see a 'security' tab so I can't change permissions.  I'm an admin, but still no tab

Check the similar solution
http://social.technet.microsoft.com/Forums/en/w7itprosecurity/thread/6c5ea353-d762-4293-85ab-88c6d3ee2c03

Hope this will help you :-)

Thanks, but please see the link you sent, it says "Under Windows 7 this no longer works, I always get "Access is denied"

I'm running Win 7 so I'll need a different fix.

Is this a new assembly or you are updating a currently added assembly.
If you are updating the current assembly, then you need to check, whether it is loaded in assembly or not

you can also try the below command
icacls c:\windows\assembly /grant my_windows_user_name:F /T /C
This works in Vista, you can check it in windows

This is a new assembly.  I tried the command line but no luck.  Here is the error message:

Access is denied.
Successfully processed 0 files; Failed processing 3739 files

have you executed command from command prompt in Adminitrator mode
i.ee\.: command prompt as "Run as Administrator"

I ran as admin and that changed things. The message is now:

Successfully processed 3482 files; Failed processing 257 files

So now it appears I have processed files in the assembly cache (GAC), but that isn't what I want to do.  What I want to do is to add a new file to the GAC.  Is there a way I can do that?