parameter cant past after authentication page

[kean yeoh via DotNetMonster.com]

hi, I am trying to past the parameter with value into an authentication
page.

for example: http://test.com/authpage.aspx?param1=value1&param2=value2

authpage is an authentication page which user need to type the login name
and password.

the problem is, after user type this link on browser and login, the
parameter will lost. same as: http://http://test.com/authpage.aspx

the parameter behind authpage.aspx is lost. Can anyone give me a hand on
this?