Contour line at specific value is not getting drawn
<p>Using the following matrices</p>

<pre><code>test1 =
[-0.200000000000000 -0.180000000000000  -0.160000000000000  -0.140000000000000  -0.120000000000000;
 -0.200000000000000 -0.180000000000000  -0.160000000000000  -0.140000000000000  -0.120000000000000];

test2 = 
[0.0153000000000000 0.0183000000000000  0.0212000000000000  0.0247000000000000  0.0281000000000000;
 0.0206000000000000 0.0227000000000000  0.0247000000000000  0.0273000000000000  0.0306000000000000];

test3 = 
[-2 -2  -2  -2  -2;
[-1 -1  -1  -1  -1];
</code></pre>

<p>(minified) I want to plot some contour lines like</p>

<pre><code>figure
contour(test1,test2,test3,[value1, value2, ...],'ShowText','on');
</code></pre>

<p>However, the contour line for <code>-2</code> is not being plotted, even when doing</p>

<pre><code>figure
contour(test1,test2,test3,[-2 -2],'ShowText','on');
</code></pre>

<p>Any ideas?</p>