To be able to record a call be sure that ctivm and ctivr are active

a res:ctivm
s p res:ctivm act:yes
a res:ctivr
sp res:ctivr act:yes

Moreover remember to set the prefences of the user, specifing a valid mail address too. i.e.:

s pref user:test on-demand-vr:yes on-demand-vr-rcpt:user@domain.it

During the call if the recording is enbaled the button of recording is clickable. Once pressed it starts blincking.