XPI install problem in Netscape 7.2

Hi all.
I use a javascript code calling InstallTrigger.install() function from
inside a javascript function. This worked fine in Netscape 6.x and
7.1, but failes in 7.2.
In my callback function I get USER_CANCELED (-210) status.
I tried to call for InstallTrigger.install() as a result of the
clicking on a link and the install process started as usual, but this
is not acceptable solution for me as I need to start the process
without any user intervention.
Does anybody know what changed since 7.1 ?

Thanks.