basic checklist if addon doesnt show up in the addon list to be enabled
1) does your mod have a description.txt? it doesnt have to contain anything
2) does your mod have a namecheck.txt? its not required, but if its there and the folder/zip name isnt the same, it wont show up
3) does your mod have a server.cs? make sure its actually of the .cs file type, not just named "server.cs" while being a different filetype!
checklist if addon can be enabled but doesnt show up ingame
1) check console log and see if executing the addon failed due to syntax errors or the like. note that ANY .cs files with syntax errors in that folder/zip will stop the addon's execution, even if the addon only executes valid .cs files!
2) if its an item/vehicle/playertype/projectile, make sure you have given the datablock a valid UI name, and that it isnt the same as another item/vehicle/playertype/projectile. if it is, both will show up in the list with the same name.
3) make sure its not using the same datablock name as another addon, it could be getting overwritten on startup.
things to check if addon is showing up but model isnt/isnt showing up right
1) check if your model is exporting correctly - use port's importer to import it
2) check if you have texture files in the folder with the dts
3) if its animated, make sure it has a root animation. it should be the first animation in the timeline