Millennials are having a party, but it seems the invitations for most teen retailers never hit their mailboxes. Perhaps that’s because such invites would’ve been issued via mobile phone. At a time when younger generations are spending upward of 80 hours a month on their mobile devices, several apparel brands are missing out on a commerce opportunity that led to $35 billion in U.S. sales last year. Such brands have been slow to enter and innovate in the mobile sector, a sluggishness that experts say could be costing them sales. Retailers including Aéropostale, Abercrombie & Fitch and American Eagle Outfitters are now scrambling for relevance among their tech-minded consumers. Some have recently added e-commerce capabilities and curated music through their mobile apps, though others haven’t gotten even that far. Read more at Advertising Age.