In Tasker, use goto Menu > More > Run An Action and see if GPS is still listed as an available option. If it is, try using it to turn GPS on or off and see if it works. If it doesn't, you'll get a warning (like I just did). This issue first appeared in Gingerbread when Google inexplicably blocked the ability for user apps to enable/disable GPS. On my Bionic and your RAZR, Motorola apparently removed this restriction. It appears that they did not do so in ICS. I just tested my GSM Nexus and got a warning.
You can apparently work around this using the Secure Settings plugin (which I use for other things), but haven't tried it on my Nexus yet. For this workaround to work you'll need to be rooted, and have either Secure Settings or its helper app installed as a system app.
