1:The file(s) included don't seem to be the right type. You can upload a .package file and/or a .sims3pack file for each of your TS3 CAS creations. Check the files and make sure you're sharing the correct file(s).
1:The file(s) included seem to be corrupt or broken.
1:Your upload is a recolour of a mesh you made yourself, but you haven't included the mesh. Make sure to attach the mesh as well, so downloaders can get all the needed files in one place. You may need to tick "new mesh" as the upload type as well, and provide additional pictures and information for your new mesh.
5:You have included a .package and/or a .sims3pack file for your TS3 CAS creations.