Difference between created and imported objects?

I’ve been working on a model from the models resource to practice with but the character had flat eyes controlled by dynamic textures so I changed it to actual eyeballs. However when I assign weight on them to a bone they don’t follow the head when posing. I’ve weight painted the entire model and made a few small edits and all of it works fine it seems like just the spawned meshes won’t react. Any idea what the problem might be?

Could you post the .blend file?

OK, I’ve taken a look at your file and all I can see is that the eyeballs aren’t parented to the armature. All you have to do is to Select the eyeball, then the armature, click Ctrl+P and choose “armature deform”. Or you instead of selecting the entire armature you could switch it to “pose mode” and highlighting the Neck bone, then parent the eyeballs to it by setting the parent to “bone”.

Or you could

Thank you for the help that solved it. However what confuses me is that when I assigned weights to the original model, I had things like the gloves, jacket, shoes etc. all as separates objects in a hierarchy from his scarf. Then I parented it to a single bone armature following a guide I found and went from there. After this I joined the meshes to a single object and as you can see in the file the Body-object is not technically parented to the armature at least according to the outliner but all the weight paint still works. The eye-meshes also didn’t complain about me assigning vertex groups with weights for a specific bone. If I try to parent the Body-object to the armature again it asks if I want to set automatic weights and whatnot again. Do you know what has happened?