@mahi2000,
The problem may be due to rendering the chart before even tab is displayed because of which dimensions for the chart are not calculated properly. You can use tab events to initialize and render the respective chart after the tab is displayed as shown in this code snippet.
$('#bs-tab2').on("shown.bs.tab",function(){
chartTab2();
$('#bs-tab2').off();
});
Please take a look at this JSFiddle for complete code.
If the problem still persists, please create a JSFiddle. So that we can look into it.
—-
Sanjoy Debnath
Team CanvasJS