Performance of LDPC Coded with OFDM -high level qam over AWGN and Rayleigh

Ihave mini project in wireless communication using matlab , i built the simulink and most of parts work and i got good results ... but there is sub-part cannot work .... the title is Performance of LDPC Coded with OFDM -high level qam over AWGN and Rayleigh channel...firstly with noisy channel all parts work in good condition .. however over rayleigh channel , I implement qam the qam with equalizer then qam with ofdm and equlizer ,i used differen subcarreir and differen doppler shift and every thing is good ,but when i apply LDPC i got error ... so if you can solve this issue i will happy ... i am ready to send my model to you to make it easy for you ,just modify configration
best regards