avoid the read befor write error in Simulink .

Hi, Please I realy need help.

I work on the decoder LDPC, and I want to model it on Simulink, so to avoid the problem of LOOP algebraic I use the memory blocks, and to avoid the read befor write error I use Unit delay . But it does not work, I always get the error.

what can I do to fix this problem??. I try it in simple Model it work But in my LDPC model it does not.

i tried to change the priority of the blocks but without results.

so is the probleme in My model or in parameters or somthing else???

thank you