title: I can't select the item in the ExtJs grid
body: <p>everyone.</p>
  
  <p>I'm using ExtJs to create a grid with more than 100 records, and I can't select/highlight one of them within the grid.
  It always select/highlight the first record when I tried to click another one.
  But when I added the new records, these items can be selected/highlighted.</p>
  
  <p>Anyone know the possible reason?</p>