Why empty Session.Property( ALL ) in Custom Action(VBScript)?

Hi.

Express Project.

I was add custom action using VBScript.
But, All return is empty.

MsgBox "111 : " & Session.Property("SETUPEXEDIR")
MsgBox "222 : " & Session.Property("SourceDir")
MsgBox "333 : " & Session.Property("INSTALLDIR")
MsgBox "444 : " & Session.Property("APPDIR")
MsgBox "555 : " & Session.Property("TARGETDIR")
MsgBox "666 : " & Session.Property("SRCDIR")
MsgBox "777 : " & Session.Property("VersionNT")
MsgBox "888 : " & Session.Property("ProductName")

What's wrong?
Hope help anyone~ please....