how to trigger a rule only during day

[orc trial]

Hi 

i have a zwave bulb that i currently have setup a rule that turns in on when a zwave motion sensor detects motion ("MS2statussensor", value == "off")

this rule works fine

what i want to do is turn the bulb off ONLY during the hours of 7 am and 7 pm when the motion sensor turns off (motion is not detected any more) ie Event ( source == "MS2statussensor", value == "off")

i have attempted to write the rule as follows below but i am not sure what cron sytax to use so the rule only gets triggered between 7 am and 7 pm as soon as  Event ( source == "MS2statussensor", value == "off") occurs. 

rule "turn bulb off during day"

timer (cron: xxxxx)

when

   Event ( source == "MS2statussensor", value == "off")

then

  execute.command("GoControlBulbOFF");

end