There's a a few different techniques for mobile web content adaption. Depending on the technique used by the page you're analyzing you way need to set a user agent so the right page is fetched.
If the page in question is build using responsive design you don't need to do anything. But if the pages servers different content based on the user agent you need to change the SeoTools http settings to be able to analyze these pages.
Change the request "User-Agent" header. For example to fake an iPhone 5 you can enter:
Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3
The Spider will inherit the global http settings but can also be customized for an individual report.