Subreceiver independence band

[pa2zz]

Hallo,
 
Why can I not get my K3 in the Subreceiver band independence mode. I get the massage in the CONFIG:VFO IND not a yes but UNAVAIL. Whats wrong?
 
Tnx Henk, pa2zz
K3/10 #0659
K2/100 #5175