With the recent Java updates, many people are having trouble with their Java Web Start apps lacking Codebase, Permissions, and Application-na
If you use Netbeans, set those attributes in your file nbproject/project.properties:
The very last one is supported only by Netbeans >= 8.0 (see here). The others should work even in Netbeans 7.2. I set jnlp.mixed.code to trusted_only too but maybe it isn't appropriate in your case. You can modify your file jnlp-impl.xml at your own risk if you can't switch to a more recent version of Netbeans.
atulsm's suggestion is better if you don't use Netbeans.