Clicking "Add line/Recalc" button on quotes, invoices, po's, etc doesn't work

I tried to create a quote and then filled all the details. When i click on the "Add line/Recalc" button, the form gets cleared and doesn't get added to the "Current quote items" section.

When i checked in firebug, the post request upon the button click returns the following code:
<fieldset><legend>Current Quote Items</legend><div class="entries"><table id="draggable-entries" class="sticky-enabled"> <tr><th></th><th></th><th></th><th></th><th></th><th></th></tr> </table> </div><div class="total"><input type="hidden" name="entries[total]" id="edit-entries-total" value="0.00" /> </div><div class="newline"><fieldset><legend>New Quote Line</legend><div class="newline"><table class="sticky-enabled"> <thead><tr><th>Stock Code</th><th>Qty</th><th>Extra Text</th><th>Price</th> </tr></thead> <tbody> <tr class="odd"><td><div class="item-desc"><div class="form-item" id="edit-entries-newline-item-desc-wrapper"> <input type="text" maxlength="255" name="entries[newline][item_desc]" id="edit-entries-newline-item-desc" size="20" value="" class="form-text form-autocomplete" /> </div> <input class="autocomplete" type="hidden" id="edit-entries-newline-item-desc-autocomplete" value="http://mysite.com/drupal/erp/item/autocomplete/sell" disabled="disabled" /></div></td><td><div class="qty"><div class="form-item" id="edit-entries-newline-qty-wrapper"> <input type="text" maxlength="6" name="entries[newline][qty]" id="edit-entries-newline-qty" size="6" value="" class="form-text" /> </div> </div></td><td><div class="extra"><div class="form-item" id="edit-entries-newline-extra-wrapper"> <textarea cols="60" rows="2" name="entries[newline][extra]" id="edit-entries-newline-extra" class="form-textarea resizable"></textarea> </div> </div></td><td><div class="price"><div class="form-item" id="edit-entries-newline-price-wrapper"> <input type="text" maxlength="12" name="entries[newline][price]" id="edit-entries-newline-price" size="12" value="" class="form-text" /> </div> </div></td> </tr> </tbody> </table> </div><input type="hidden" name="entries[newline][item]" id="edit-entries-newline-item" value="" /> <div class="addline"><input type="submit" name="addline" id="edit-entries-newline-addline" value="Add line/Recalc" class="form-submit" /> </div></fieldset> </div></fieldset>

Probably the output is not being able to replace in the target wrapper.

I created a item, added stock & store to it. Also added a customer & a supplier too. Tried with garland theme and also the erp_theme.