Here are some general tips:
- Try to take the folder with the addon out from the wow/interface/addon folder, starting the game, check if everything is ok and adding the folder again
- If you are currently using any more addons, take them out just to check if it's not a compability issue. (Dogmaxui might be conflicting with another addon)
- If you still are using the default 32MB in the memory storage for addons, increase it. (I suggest 256MB as interface addons sometimes can be very consuming and dependent of this value)
- If you downloaded a .zip or .rar file try unzipping it again (as files sometimes can become corrupted through the process of unzipping)
- Try downloading the addon from another source. (the one you have can have some sort of error or also be corrupted)
Hope it helped. If not, I advise you to post some screenshots of the issue, maybe reveal your computer's specs and like LYQ said, show "an entire addonlisting".
Best of luck.