A tab set with nested tabs breaks with tabs('add',...)

Scenario:

When I have a tab set with id="main-set" which has four tabs

| one | two | three | four |

With nested tabs in tab 'three' with id="nested-set". This tab loads a page that contains the following tabs via AJAX.

| a | b | c |

1. Action:

var index = $("#main-set").tabs('length');

$("#main-set").tabs('add',url,"five",index);

1. Expected Result:

| one | two | three | four | five |

$("#main-set").tabs('length') == 5

1. Actual Result:

| one | two | three | four | five |

$("#main-set").tabs('length') == 8

Conclusion:

It seems that the tabs begin to incorporate the nested tabs into its count. Also the content of tab "three" was messed up. When I click on the tabs 'a', 'b', or 'c' it does not display those nested tabs' content it actually closes the tab 'three'. I suspect that it actually trying to display the tab of that index in the 'main-set'