The error is siimple, you are trying to save more number of elements than the array is initialized for.
A = zeros(2,3) ; % 2x3 matrix is initialized
A(1,:) = rand(1,2) ; % no error, 1 1x2 array is saved
A(2,:) = rand(1,3) ; % error, you cannot save 1x3 array into 1x2
In the same, way check your initialized array dimensions. If you are sure of array size, initiailze it as a matrix. If not initialize it as cell .
B = cell(2,1) ;
B{1} = rand(1,2) ;
B{2} = rand(1,3) ;
