you have to submit a web case to go pas the registration limit
go here
http://www.adobe.com/support/digitaleditions/
sign in with your adobe id of course, then click submit a web case on the right. tell them about trying the app etc and that you need to reset your limit so you can activate the 950
they'll fix it up for you. may take a few days . i have hit it several times now what with trying new devices and some updated firmwares being seen as new devices. they always fix it up.