No event trigger after casting session variable in OnPreInit

[=?Utf-8?B?R2Vvc3Ns?=]

Dear All,
I try to change a master page in the OnPreInit in a asp.net page.
(Session variable is guaranteed to have been assigned)

protected override void OnPreInit(EventArgs e){
if ((bool)session["IsNew"]){
this.MasterPageFile = "~/NewMaster.master";
}
else{
this.MasterPageFile = "~/OrigianlMaster.master";
}
base.OnPreInit(e)
}

But after this, the page does not trigger any other event. I try to trace to
the problem , and when I remove the casting of the session variable,
if ((bool)session["IsNew"]){
to
if (session["IsNew"] == null)

then, everything works fine again.

Why casting a session variable will inhibit the triggering of other events
in the page??

[=?Utf-8?B?YnJ1Y2UgYmFya2Vy?=]

becuase casting a null to bool throws an exception, and stops page processing.

-- bruce (sqlwork.com)
"Geossl" wrote:

Dear All,
I try to change a master page in the OnPreInit in a asp.net page.
(Session variable is guaranteed to have been assigned)

protected override void OnPreInit(EventArgs e){
if ((bool)session["IsNew"]){
this.MasterPageFile = "~/NewMaster.master";
}
else{
this.MasterPageFile = "~/OrigianlMaster.master";
}
base.OnPreInit(e)
}

But after this, the page does not trigger any other event. I try to trace to
the problem , and when I remove the casting of the session variable,
if ((bool)session["IsNew"]){
to
if (session["IsNew"] == null)

then, everything works fine again.

Why casting a session variable will inhibit the triggering of other events
in the page??

[=?Utf-8?B?R2Vvc3Ns?=]

As I have mentioned, the session variable is guaranteed being assinged. Not
null pointer exception....

"bruce barker" wrote:

becuase casting a null to bool throws an exception, and stops page processing.

-- bruce (sqlwork.com)
"Geossl" wrote:

Dear All,
I try to change a master page in the OnPreInit in a asp.net page.
(Session variable is guaranteed to have been assigned)

protected override void OnPreInit(EventArgs e){
if ((bool)session["IsNew"]){
this.MasterPageFile = "~/NewMaster.master";
}
else{
this.MasterPageFile = "~/OrigianlMaster.master";
}
base.OnPreInit(e)
}

But after this, the page does not trigger any other event. I try to trace to
the problem , and when I remove the casting of the session variable,
if ((bool)session["IsNew"]){
to
if (session["IsNew"] == null)

then, everything works fine again.

Why casting a session variable will inhibit the triggering of other events
in the page??