Ajax UpdatePanel with Wizard

[Guest]

Hi,

I have a Wizard that have about 5 steps and in every step (page) I do have
some tables, checkboxes, gridview...etc and I'm trying to Cut and Paste this
wizard into Ajax UpdatePanel for Ajax enabling, but it's giving me this
error:
"The ActiveStepIndex must be less than WizardSteps.Count and at least -1.
For dynamically added steps, make sure they are added before or in
Page_PreInit event"
and when I took out the step(page) that have my gridview in it every thing
worked fine!!!?
So, Why is that?

Thanks