I am going through the Trailhead lessons and for some reason am hung up on this one.  The test is to:
Create a Visualforce page that displays the first name of the logged-in user.
* The page must be named 'myHelloWorldVF'.
* The displayed user information must be generated dynamically from the logged-in user.

The code I have for this is:
<apex:page >
    {! $User.FirstName}
</apex:page>

For some reason Trailhead keeps coming back with the error:
The Visualforce page did not fit the criteria. The first name of the logged in user was not output using dynamic global variables.

Can anyone give insight into what I am doing wrong?  Not looking for the answer, just guidence in what needs to be looked at.

Thanks!

I am going through the Trailhead lessons and for some reason am hung up on this one.  The test is to:
Create a Visualforce page that displays the first name of the logged-in user.
* The page must be named 'myHelloWorldVF'.
* The displayed user information must be generated dynamically from the logged-in user.

The code I have for this is:
<apex:page >
    {! $User.FirstName}
</apex:page>

For some reason Trailhead keeps coming back with the error:
The Visualforce page did not fit the criteria. The first name of the logged in user was not output using dynamic global variables.

Can anyone give insight into what I am doing wrong?  Not looking for the answer, just guidence in what needs to be looked at.

Thanks!