Page 2 attribute in Agile 9.3 invisible in Modify Privilege choices list

 Hi, In Agile 9.3 i've created a list  attribute called "Create user"  on page 2 under Change Requests and assigned the list of users to this attribute.  The default value is set to $USER for this attribute. Assumign it'll populate this value automatically a CR has been crete and the create User attribute has a "no privilege" hyphen beside it. I tried to add it in the modify privilege of the subclass but the Change Request.Page Two.Create user  is not in the choices list while all other attributes for Page two are shown and have been selected and editable in the subclass, as a result of this I'm unable to populate the CreateUser value. Can someone please let me know what did i do wrong in setting this up?