Also, please look in the Dynamo console for any errors loading your package - this thread reminds me of:
though it could be unrelated.
Also - did you enable CLR exceptions in the exceptions setting dialog? You will want to do this before dynamo starts loading your package.
When you say the dll is loaded, do you mean your zero touch dll, or the dll is depends on?
In the case of this thread the referenced dll was blocked on the machine and when manually copied to the bin folder was not loaded.(it was when it was loaded using copy local) I would investigate unblocking it - since you seem to have a similar symptoms (cause could be different of course).
If you provide a repro project I will check it out.