It seems you are not the only one with that problem. As of today may 28th, I am still waiting to receive Dragon #356. I left a message at customer service yesterday but since this post is on the same topic I decided to try overhere as well.
There is no bad feelings on my part. I just hope you will be able to straighten this out and ship my missing issue soon.
This is a great time to be with Paizo (the final issues of Dragon and Dungeon and the start of a new product) I just dont want to miss any of this.
Thanks