Cd-DVD Speed won't "write disk" with Plextor

As the title stated, I can no longer create a test write using either Plextor DVD 712 or 716 with CD-DVD Speed. The write button is grayed out. I am fairly certain that I could use this option before, while I was never able to pie scan disks due to lack of support of plextor. What could be the reason for this? Anyone else?

Thanks!