https://confluence.atlassian.com/display/GH/Supported+Platforms

The requirements for the latest stable release of jira (on premises) state that it works with JRE 1.6 and 1.7
According to the installation notes on your website, greenhopper 6.0.4 is supposed to work with the latest version of JIRA.
I tried to install greenhopper on top of the latest stable release of jira (on premises) with Sun JRE 1.7 update 7, but couldnt activate.
The error message was quite unhelpful, telling me there was a problem contacting the jira server, there was a problem with the license etc.
There was an indication to check the log files, but nowhere is the location of these files disclosed.
I had to snoop around for quite some time and eventually found a line in a log file indicating a module used by greenhopper needed to be a particalur version which research lead me to find this meant JRE 1.6 was required.
After installing JRE 1.6 greenhopper works.
For the sake of keeping your customers happy, I strongly advise that you

• correct the documentation for greenhopper installation to include the proper requirements for a successful installation (a greenhopper problem)
• provide some indication of log file location from the user interface (a jira problem)
• provide better module error messages (a jira problem)