Please check out this sample code given below: 
<chart showValues='0' connectNullData='1'>       <set label='Jan' value='420' />       <set label='Feb' value='295' />       <set label='Mar' value='523' />       <set label='Apr' value='473' />       <set label='May' />       <set label='Jun' />       <set label='Jul' value='354' />       <set label='Aug' value='457' />       <set label='Sep' value='127' />       <set label='Oct' value='354' />       <set label='Nov' value='485' />       <set label='Dec' value='486' />   </chart> 
Hope it may help you.