If you try to encode bits and then tries to take advantage of entanglement, then even though there is a correlation when the outcome of the measurement from both subsystems were obtained and compared, to any subsystem, all they see is just random instance of 0 and 1 with no pattern whatsoever.
That is, the outcomes only look correlated when viewed with both systems taken account of, in any individual system, the result is a statistical mixture. Since you cannot control the outcome of the measurement of the individual subsystems, you cannot encode any bits on it and hence cannot send a message