CCSDS 27 encoder/decoder

Hello Gnuradio Community,

I am working with the Gnuradio CCSDS 27 encoder/decoder blocks in Gnuradio ver 3.8. To ensure I understand these blocks, I fed a random signal from  0-255 into the encoder with an embedded Python block between the encoder and decoder which converts the bit values 0 and 1 leaving the encoder into -1 and +1 for the decoder. I use file sinks to collect the byte values (between 0-255) entering the encoder and collect those leaving the decoder and compare them to validate proper working functioning. Works good!!! 

Next, appropriate blocks comprising QPSK modulator/demodulator were inserted between the CCSDS 27 encoder/decoder. At this point I could not get the output of the decoder to equal to the input of the encoder. I have tried everything, the latest being the decomposition of data (input and output) down to the bit level and put in a delay to see if I can find synchronization between the input and output bit values. I have attached my grc flowgraph.

I will appreciate any help.

Regards,

George