Binary Rectangular PAM Simulink

I am facing a problem in setting the sample time for gain block and Additive White Gaussian Noise block connected together (<http://tinypic.com/view.php?pic=zmzdb6&s=6)>. While running the model, I am getting a block error specifying that, "The sample time 1e-09 of AWGN Channel/Dynamic AWGN at input port 1 is different from the sample time 0.001 of Gain at output port 1", even though I did set the sample time as 0.001 for Gain block as well as AWGN block. This problem is only occuring when ever AWGN block is getting connected to Sample and Hold block which takes its input from Pulse Generator block. What do you think could be the problem?