Need more info, what system, what OS?

I have the same problem. Im running Win2009R264 on a PE2950.  OS has all MS updates as of today.

Correct.  I click on Upgrade.  The dialogue box appears "The following component(s) will be Updated:".  I click on the "Yes" button and the dialogue box disappears and nothing happens.

When you click upgrade, immediately afterwards you should get a confirmation message before it actually starts the upgrade, do you see that and then nothing?

I have seen the update disk get stuck on one of the updates and exhibit similar behavior.  I suggest unchecking all but one update and trying that.  Usually firmware updates are the most reliable, so I suggest trying those first.  Some drivers and OMSA sometimes need a manual uninstall before the new version can be installed.

I also tried running as administrator and the same thing happened.

try this, go to a command prompt and try running SUU via the command line. suu -u will start the app in cli mode. if you can, post a scrceen shot and or the suu.log file from the c:\dell\suu folder

I think I just figured it out.  The ISO is only 1.69GB and 6.2.1 was over 4GB.  I remember downloading multiple files last time and not for 6.4.0. 

I need to look at the downloads again and download all files for 6.4.0. then create one file out of them, then burn the DVD.

The 6.4.0 update DVD is working.  I downloaded all the ISO files and ran the "copy /b om* om640_suu_a00.iso" as shown in the "Installation Instructions".  I then burned that one ISO to DL-DVD and the update ran successfully.