well i wanted to write you that it should just work now. but then i read the datasheet you provided a third time :-)sending and receiving probably works right now. the problem is your receiver's output signal. it's 0 volts for LOW but only 0.8 volts for a HIGH. arduino expects 5V with a little (!) tolerance. you need to amplify the signal, which should be no hard task. but i don't think i'm the best person to help you here. i guess a single transistor could do the job. there should be plenty of infos on the internet.keep us updated!best, kuk
are both boards connected on ground?