means u r directly connecting data output of HT12E to data input of HT12D using wire?
have u connected the ground wire?
if yes and still u r not getting output then there is miss match in address at both side. connect all address pins A0-A7 on both sides to ground.
for matching clock frequency
at HT12E side use 1.1 M ohm resistor
at HT12D side use 51 K ohm resistor