With full admin privileges, you should be equivalent to the superuser/root, and should not need to use sudo to install. In any case, I've had distros get a little screwy with sudo when there have been root-privileged users in different groups - so one suggestion would be to ensure that your japrime user is also part of the root group. Also, is your username in /etc/sudoers? Being privileged, but not listed in the file might also be causing your issue. Finally check your system logs for insight as to why your attempts are failing. If your ID is not in sudoers the sudo attempts should be logged to /var/log/auth (in Ubuntu 10.04, anyway).
My recommendation would be to reduce the privilege level of japrime, make sure japrime is in /etc/sudoers, and use sudo to execute in those instances where the mighty-mighty is required. Having too many root-privileged users can be a security nightmare later.