why imhist() function showing error

Error using imhist Expected input number 1, I or X, to be two-dimensional.

Error in imhist>parse_inputs (line 278) validateattributes(a, {'double','uint8','int8','logical','uint16','int16','single','uint32', 'int32'}, ...

ERROR Error in imhist (line 60) [a, n, isScaled, top, map] = parse_inputs(varargin{:});

Error in Untitled3 (line 3) imhist(A)

CODE

A=imread('D:\test.jpg'); subplot(221);image(A) subplot(222);imhist(A)