I'm running dd-wrt.v24-16785_NEWD-2_K2.6_big-e2k-e3k.bin on a Linksys E2000 with no problems. I've used the latest Firmware Modification Kit (with the -ng scripts) to build a new version where I've added an init script, and modified to MOTD to show my customer version.
After I create the new binary, I use the scripts to extract that binary to verify all my changes are in there. They are. Then I upload the binary using the "Firmware Upgrade" page in the GUI.
I get no failure messages, warnings, or errors of any kind at any point in this process. After the Linksys reboots, I see that my init script is not on the filesystem and the MOTD is still the original.
Does it sound like I'm forgetting something? Shouldn't I get an alert that the upgrade failed if my new binary is invalid?