Updated to Dell BIOS with SLIC 2.1 added, Windows 7 will not activate

After updating my Dell Optiplex 330 to BIOS A11 with SLIC 2.1 added, I attempted to activate Windows 7. I followed this method:

techdoors.wordpress.com/2012/09/26/activating-windows-7-oem-way/

I have installed the Dell certificate with slmgr. I have verified the SLIC 2.1 table is installed via SLIC_Toolkit, which shows “Dump OK ! ( DELLB9K_V2.1 )”. When I load the Dell certificate in SLIC_Toolkit, I get a green light on the key. Everything looks good, right?

I then tried activating with the key shown in SLIC_Toolkit, and also one found at a link at the site listed above. Both times the activation failed, saying the key was not valid to activate Windows. I then tried Anytime Upgrade with the Dell Windows 7 Ultimate key, which also failed to activate.

I'm at a loss, as the directions were very straightforward and it appeared that everything went successfully... except the most important last step. Any ideas where to go from here to get this machine activated?

 

2 things:

1. I thought the whole point of OEM BIOS modding was so you could avoid needing loaders. I'd prefer to only use a loader as an absolute last resort.
2. When I look in the BIOS, the service tag shows as blank. Could this cause a problem with activation? I thought I read somewhere that you may need to change your service tag to fix activation issues on Dell's.