Make sure you are logging into the correct region. characters on one region will not be present on the other regions. Regions are americas, europe, and Asia. it is the drop down menu right above the play button. If still not see if you are logged in with the correct account. I.E. you accidentaly loged into your yahoo account instead of your gmail account with the same name.
These are the two most common i have seen in the diablo blue trackers.