How to get buildnumber / revision from Assembly? (4th digit)

Our build process updates the forth digit (buildnumber or revision) of the version number on every build.

I'm using the following code to try and get the version so that it can be displayed on the splash screen and about page.

var version = Assembly.GetEntryAssembly().GetName().Version;
var programName = "Version: " + version;

How come the 4th digit in the version number is always zero, and what can I change to get it to property reflect the build number?