You can't even be on rollerskates. It should work when you're off them.
Are you riding the roller blades when trying to activate it? The Pokeradar won't work if you're on roller blades (you have to use the D-Pad to walk around).
Now I'm not up to this part but this is not the first time I read of this issue.
How are you moving the character. Using the circle pad or the Dpad?
If your using the circle pad, you can't chain because your wearing skates from what I heard. The Dpad has to be used.
I might try and hunt up some solutions for you to try and help you out if this isn't the issue.