On the incident window I set my Raise User field to show as a hyperlink.
I want my Analyst to be able to hit this hyperlink to create a new user, but the hyperlink disappears when no user is selected.
This is a privilege issue. If the Analyst doesn't have the privilege to create a new User, then the hyperlink will not show if a User hasn't been selected in the drop down list. To activate the Hyperlink you will need to give the Analysts quite a few of the privilege under "System - Non Process Related Objects"
Go to the Administration Component, highlight the relevant Role and select Privilege.
Expand Modules - System - Non Process Related Objects"
Activate the "Create" privilege on "User", "Password" and "Licence Audit Item".
For creating an Analyst, they also need the "Create" privilege on "Analyst". For creating an End User, they also need the "Create" privilege on "End User".
They will also need privilege for the fields on the User Account window, that they want to fill in which are privileged, such as "Phone Number".
However if you are missing any privilege you will when testing this get an error message letting you know which privilege you are missing.
For more information on Privilege, please see here.