Digital BW, The Print

I'm running the 1280 with CIS and Piezotone inks.  The lights on the 
printer started flashing (red and green alternating) which is 
supposed to indicate low ink.  Although the Epson software 
shows "both carts full", I tried pressing the yellow button to move 
the cartrige carrier to the left, thinking I would remove and 
reinsert the CIS carts to fool the machine into thinking I was 
replacing the carts.  The carrier will not move.

Any ideas?  Could it just be the yellow button isn't working?

Thanks in advance for any help you can provide...Val