title: Why vim source _vimrc doesn't work while deleting some configurations but work for adding some?
body: <p>In my _vimrc i uncomment the line <code>" noremap  &lt;a-j&gt; :m+&lt;CR&gt;</code>, then execute <code>:w</code> <code>:so %</code> the map works well. Whereas, the map still works when i comment the line back and execute <code>:w</code> <code>:so %</code> like before. Have i done something wrong?</p>