When working with IDX please remember to follow these several simple steps to make sure your pages are displayed properly.
Go to Theme Options > IDX Pages. Here you can choose page template for IDX plugin pages. There are options for IDXBroker and iHomefinder.
Also, you can set up the template while you editing the page. On the right side of the page under the Document tab find the Template section and choose the relevant IDX template.
If you don't specify the template for IDX pages, the pages might be displayed incorrectly.