I have just purchased several of these 48 port 4 SFP switches that connects to a 3750 12 port SFP switch that i also purchased. I cant seem to get them to talk to each other one side lights up while the other doesnt i have try several things cant get...

I have just purchased several 3750 48 port switches with 4 SFP and 1 3750 12 port GIGabit switch and i can only get one side activity at a time. can some one help me out tell me what I am missing? thanks