MMSE channel estimation in DVB-H ofdm

Hi all!! I am performing LS & MMSE channel estimation in an OFDM system
with the DVB-H parameters, where the pilots are not equally spaced as the
case with WIMAX. I am facing a severe problem as the BER of both MMSE and
LS are identical. I am sure that the LS is correct and that the problem is
with MMSE. I've tried everything to make a difference between them. The
only  successful attempt was to increase the variance to 100 which is
absolutely wrong as it shouldn't exceed 1. Could the problem be with the
DVB-H parameters or is there something i'm probably performing incorrectly.
  Please if anyone knows what's the reason behind this or if anyone could
help me deal with this problem, please contact me on my
email:mooshi88@gmail.com. I am really tight in time so please help me
ASAP!!