GPM 205 Sd.Kfz.251/1 Ausf.C

Dear All,

I am now constructing GPM 205 Sd.Kfz.251/1 Ausf.C and found there are some problems in its cockpit:

I do not know how to put part 12 and part 12a together ?

Is there someone who has the experience can show me how ?

Thanks!!