Last year, Forrester predicted that U.S. brands will spend $2.7B on their social media marketing efforts by the end of 2013, with that number growing to $5B by 2016. And with one in five of all Internet clicks in the U.S. happening on Facebook, brands are taking the cultivation and engagement of their fan base on Facebook seriously.

But unless brands wake up to their Facebook “mobile problem,” they will waste significant marketing dollars as well as audience clicks. The mobile problem I’m talking about is, surprisingly, unrelated to Facebook mobile advertising.

And it’s an issue that has yet to be widely discussed. Brands have been quietly struggling to engage with their Facebook fans who connect with them from a mobile device. We recently conducted a field review that illustrated that Facebook promotional apps on seven of the top ten most popular brand fan pages failed to successfully engage mobile fans.

See the article written for Friend2Friend and successfully placed at MediaPost on this critical subject.