How do we help our puppy's anxiety in his crate?

My wife and I got a brand-new puppy about a month ago, and he's been dealing with anxious crate behavior since day 1. He's about 3 1/2 months old now, and every time we put him up in his crate to go to work, he cries and yelps and barks like we're shipping him off. He also pees in his crate at least once a day.

We've tried everything from giving him a big treat he only gets in his crate, taking everything out of his crate, shrinking the crate to the appropriate size, moving it towards a window, putting music and/or TV on while we're away—you name it. But no matter what we do, he always acts like we're leaving him forever. Keep in mind, we have a dog walker come twice a day, and one of us comes home at lunch—so he's never alone for more than 2 1/2 hours.

We don't know what else to do to help our little guy feel comfortable and calm when we're not home...any suggestions would be very VERY welcome!

Thank you!!