Node missing

Hi there,

We've developed several nodes (but I'm pretty new to the development) and now I have a strange problem and no one could solve it so far:

A node is missing in the node repository. The jar-File is in the plugins- directory and there seems to be no problem with it. For other Knime applications the same jar does it's job... (copy / paste)

If I export the plugin as directory instead of a jar, the node appears. Is there any explanation for this weird behaviour?

Antje