Condition for "Display the specific dialog" event

[i.makar]

Hello everyone!
I would like to perform the verification of the installer property at certain installation step. And force user to re-enter the data, that is Click on the Next button would show an error message and user stay on the same dialog until inputted data are verified.
I expected that writing the Condition for the Next button event (Display the specific dialog) is OK.
However, after I typed any condition in the Display Specific Dialog of the Button control, the Advanced Installer shows me the "Error field error. Please add an appropriate value in this mandatory field"

Thanks
Ihor

[i.makar]

It seems I've found an workaround in this thread:
http://www.advancedinstaller.com/forums ... =2&t=23472