Husband is closed off.

Chy
My husband struggles to open up to me about things. He was possibly expecting a promotion at work. When I asked for an update he acted weird about it and didn't want to tell me anything. When his brother asked him about it later he seemed fine to tell him about it. 
I am just confused as to why he wouldn't want to be open with me about it. This is just one example but he makes jokes and brushes things off when it comes to a lot of topics. 
My point is that I would like some tips on how you help your significant other open up about things. I can't help but wonder if I create an environment that makes it hard for my husband to talk to me. I am not taking all the responsibility obviously but any advice would be great! Please help!