"Verify that parent properties match..."

[stevol]

I have registered the login in a website. While registering, I clicked "Yes" in 2 protection advice boxes.
When I run the test, I obtain Run Error:
Cannot find the "Sì" object's parent "Avviso di protezione" (class Dialog). Verify that parent properties match an object currently displayed in you application.

In the Expert View, I see (xyz is an organization):
..

Code:

Browser("xyz").Dialog("Avviso di protezione").WinButton("Sì").Click
Browser("xyz").Dialog("Avviso di protezione").WinButton("Sì").Click

..
in which the error is in the second line. How can I resolve the problem? (and which is the meaning of the error?).
thx :-)