Hydrogen/Jack error

Hi, I’m new to linux/jad. I installed JAD 1.0 a couple of days ago and I am having some problems. When I open hydrogen I get an error message: Jack driver: error in port register. I’m using version 0.9.4-svn (development version) After clicking on ok/x about 20 times hydrogen will run. I get the same error message when opening a new project/demo. Any ideas?

thanks in advance.