Here are some things you can try…
1.) A common cause of this problem is deleting a page titled “Search” which is auto-generated after installation of our plugin. Restore this page under the Pages section in WordPress…
2.) In WordPress go to Settings>flexmls IDX and click on the Behavior tab (upper-left of the page).
Under “Open IDX Links” there will be a drop list of pages on your site. Make note of the page that is currently selected.
Then click on “View The Documentation”, copy the shortcode…
[idx_frame width='100%' height='600']
Now go edit the page that is selected in the drop list above and make sure that short code is in it.
3.) If #1 didn’t work, go back to the Behavior tab and check the setting.
Some themes or plugins override our code, this setting will help push ours forward so the search results page works.
4.) Under Settings>Permalinks in wordpress, set it to Post Name.
This will put the page names in the URL, instead of having ?page_id=23. Having the page names in the URL is also helpful for search engine crawlers.
5.) You may be using an SEO plugin that has permalink cleaning turned on. This should be turned off as it will remove sections of the listing links.