Because that forum was originally for ADF Mobile Preview, it now appears to have been closed.
The "preview" aspect is what you need to note about the forum topics there.
(The software has seemingly evolved beyond the "preview" stage.)
The forum appears to have been closed on 19-Oct-2012.
There is an announcement post at the top of that forum entitled...
+"Where to post ADF Mobile specific questions now?"+
That announcement states:
"Please leverage the ADF/JDeveloper Forum (https://forums.oracle.com/forums/forum.jspa?forumID=83), and include ADF Mobile in the title. "
Just use the normal forum and be sure to include "ADF Mobile" in the title of your posting.