The RadWizard control's known limitations are listed below:
RadWizard is not supported in IE8, since its callouts are rendered by "transform" CSS property, which is supported in IE9+
WizardSteps.Insert() method should not be used for inserting new RadWizard steps
Using the RadWizard1.WizardSteps.Insert(index, newWizardStep) server-side method of the WizardSteps collection would lead to corruption of the control tree of the page. In consequence, it could prevent the viewstate to be loaded properly. As a result the application crashes after the postback. The WizardSteps collection's Add() server-side method (RadWizard1.WizardSteps.Add()) should be used instead, as demonstrated in the Add/Remove Wizard Steps demo.