phase shift beamformer

Hi every one

I am doing work on narrow band phase shift beamforming (frequency domain)
and after doing various simulations, i decided to varify beamformer
practically. I was able to get data from an acoustic  linear array of 24
elements spaced 0.17m apart. The omni directional source was placed at
various bearings w.r.t linear array and was transmitting 4.4KHz CW pulses
of 200ms duration . The linear array sensors were simulataneously sampled
at 48 Ksamp/s/channel. Both linear array and source were deployed at 5-6m
depth whereas total average bottom depth at trial locatin was 12m. The
distance b/w array and source was approx. 700m.   

The problem i face is that beamformer shows peaks of nearly equal strength
at two or more well separated bearings (at approximately same range)
instead of one(where actual source was located). I dont know whether
problem is with my beamformer or with array data or with environmental
conditions (multipaths or reflections from surface/bottom due to lesser
depths)

If some one has done work on narrow band phase shift beam forming and is
kind enough to help me, he may contact me on email(abrahamnick73@yahoo.com)
to get array data (as i don't know how to attach it here in this post),
process the data and send me results in form of time vs bearing  plot so
that i can compare it with mine and reach some conclusion.

Thanks

Best Regards