Dear sir<br>         when i am running the  <strong><a style="font-weight:normal" name="tex2html132" href="http://salilab.org/modeller/9.9/examples/commands/mutate_selection.py">mutate_selection.py</a>   command i got the error selection contains no atom. what does it means<span style="font-weight:normal">.</span><br style="font-weight:normal">
<span style="font-weight:normal">         plz help me.</span><br></strong>