3D histogram problem when deal with int16 image

Hi，everyone I met a strange problem when dealing with a histogram of a 3D image.My purpose is to obtain a histogram of a 3D image.It works well on a standard image,but,occuring problem when applied to another one.following are my images and simple code.

clc; clear;

file1='HFH_001.hdr';

A=analyze75read(file1);

B=A(:);

imhist(B);

>>HFH_001.hdr can be loaded here http://www.kuaipan.cn/home.htm>user_name:[e-mail]

password:violence

class(HFH_001.hdr) equals int16,the intensity ranges from 0 to 407.But when applied to the

code,the histogram only have one value:128,I don't know why.Would you help me.

Thanks.

[Image Analyst]

Please do "whos B" and tell us what it says.