Let me share here for others to have access to:-
WHEN linking/associating an existing Registration to a file (text, pdf, wave, midifile, Mp3, Mp4 ... etc) on the SD7/SD40, please proceed as follows:-
* Select Registration.
* Load
* Turn off Reg
* Select Player
* TURN WHEEL TO HIGHLIGHT THE FILE YOU WANT TO LINK (do not TOUCH IT!!!)
* Press SAVE - REGIS
* File will be linked.
Thanks,

these are the quick tips we need thanx AJ