I can not fix this bug, it's something that's in the client. The developers added a new update in the client where Poll booth boxes would immidiately be closed once opened. It seems like they added depositboxes into there aswell. I've posted several bug reports on this issue and that's the most i can do on the matter of them fixing it.
Please try this client, it works for me when testing the script --> http://s000.tinyupload.com/index.php?file_id=00382358601544530823
if it still doesn't work with that client (it should tho) tell me then i'll try to figure out a way to deposit the items in a different way.