I've gotten HTML5 on the iPad to show the Correct and Incorrect messages, but it can be a bit inconsistent.
If this project was not created from scratch in your current version of Cp, but was upgraded from an earlier version, there may be some incompatibility introduced during the upgrade.
Try creating a small test project from scratch in Cp 6.01 and test if that works as expected on the iPad. If it does, then you may need to rebuild your quiz questions.
