Speex dev - Aug 2010 - recorded and played frame synchronization issue

I did the following tests with the echo canceler, and realized that echo 
cancellation is not possible

1. Variable change of offset between 0 and 1 frame. Result: NO echo is canceled 
at all

2. Constant offset of 1 frame. Result: NO echo is canceled neither

3. Offset of 1 frame each 10 frames. Result: Some echo is canceled, but creates 
a bit of background noise.

Does anyone know what I could take a look at that could help me?

Thanks in advance,

Andre

>Regarding the echo canceler, how well should the recorded frame be
synchronized
>with the played frame? Would it work if the recorded and played frames
passed to
>
>function speex_echo_cancellation are not synchronized, but there is a
changing
>offset between - 20 ms and + 20 ms?
>
>Thanks in advance,
>
>Andre