rear window heater problem

my rear window heater does'nt work
i've sort of investigated but i'm stumped, should i have a relay for it in the cab fuse box. Where the relay should be there is nothing, ie i just have two yellow relays in the cab fusebox not 3 as in the workshop manual. the relay for the heater is not there. Its a 96 defender. Is this the problem?

thanks
i think i might take it to a lecky friend rather than kill myself over that one
cheers