I have several versions of Java installed; it so happens that the default is Java 1.4.2.
This does not seem to be a problem for Directory Server, which found the Java 1.6 JRE and updated the .ini file accordingly, but Studio does not do this.
The Studio installation program could be enhanced to create the appropriate entry in the ini file.
Failing that, I suggest that a sample ini file be included in the installation with examples of possible entries.
Might be a good idea to include one anyway.