Issues in trying to set up a DVB-S2 transmission chain starting from available demo

I would like to extend the Simulink DVB-S2 demo in order to include some typical channel impairments. However, these involve the addition of delays in the transmission chain, which make the Mathworks implementation stop working properly.

Consider the two snapshots here below. Just by adding a trivial unit delay there are some errors arising at both the BBFRAME buffering and at the LDPC decoding levels. Of course I changed the delays in the error rate calculations, to align the data streams. Could anybody give me an explanation for this?

https://dl.dropboxusercontent.com/u/43801933/issue1.PNG https://dl.dropboxusercontent.com/u/43801933/issue2.PNG