User Extensions/Externals

[Graham & Heather Harrison]

In the first rev lesson on externals at http://lessons.runrev.com/spaces/lessons/buckets/784/lessons/7116-How-to-safely-attach-an-external-to-your-stack, after saving the stack this statement is issued:

send "revert" to me in 5 ticks -- the equivalent of quit then restart.

When I use this under rev 4.0.0 on  Mac OS X 10.6.3, it causes the card to go into strobe mode. Any explanations?