quiver3 and vector length

Hello !

I've got a problem when plotting a vector field with quiver3. My z compounds are about 1e-10 T but when plotted into quiver, it appears to be 1e-03 T which is a big difference ! (Symmetrically, when it's about 1 T in the vector, it's 1e-03 T plotted whith quiver).

Here is some data :

The z-compounds :

   1.0e-09 *

   -0.4670
   -0.4328
   -0.3918
   -0.3447
   -0.2923
   -0.2355
   -0.1753
   -0.1126
   -0.0485
    0.0160
    0.0798
    0.1421
    0.2017
    0.2579
    0.3098
and so on...

As you can see, some are positive and other negative but when plotted, it seems everything is the same...

Here is the plot :

And finally, here is the code with some explanation :

figure(1);
    quiver3(position_bobine(:,1), position_bobine(:,2),position_bobine(:,3),B_elem(:,1),B_elem(:,2),B_elem(:,3));
    hold on
    plot3(aimant(:,1), aimant(:,2), aimant(:,3),'.b')
    hold on
    pts1 = position_bobine-orientation_bobine/2;
    pts2 = position_bobine+orientation_bobine/2;
    plot3( [pts1(:,1), pts2(:,1)]', [pts1(:,2), pts2(:,2)]', [pts1(:,3), pts2(:,3)]', '.-r');    
    axis([-0.02 0.02 -0.02 0.02 -5e-3 5e-3]);
    xlabel('x'), ylabel('y'), zlabel('z');
    title('Vector magnetic field around the coil');
    hold off

Where position_bobine is a 50*3 matrix, as well as B_elem and the first function plot3 just plot the magnet and the second the coil. (On the grpah upper, the magnet seems to be too away from the center, it's normal). The z-compounds given beyond are given by B_elem(:,3)

I hope you'll be able to help me, thanks in advance.

Edit: after a few tests, the problem seems to happend when modifying axes...