for help.Run a test to login,and then it didn't jump to another page

[maosilu]

Description
The test website is HP's Sample Application:http://newtours.demoaut.com/
Here are test scripts:

Code:

Browser("Welcome: Mercury Tours").Page("Welcome: Mercury Tours").WebEdit("userName").Set "tutorial"
Browser("Welcome: Mercury Tours").Page("Welcome: Mercury Tours").WebEdit("password").SetSecure "52731305a23bf2a07fcb1eeec618a4355c6ae1bd8782"
Browser("Welcome: Mercury Tours").Page("Welcome: Mercury Tours").Image("Sign-In").Click

The Question is as following.
When the third step-click the ImageButton "Sing-in" runs over,the Webpage should jump to another page,but it didn't, and I don't know why.
Operating System:Win7,IE 9,UFT
please help me here.