Why isn't my beer pouring after tapping a new keg?

There are a few areas to note if a brand new keg of beer will not pour after changing it

1. Make sure to have bled your FOB after the keg change.  See how to Bleed a FOB, and observe the position of the FOB in the chamber.  Compare to the photos below - it should be all the way to the top and full!
   
2. Shut off valves may not have been reopened after the keg change.  Compare to the photos below - all of the valves must be completely parallel to the line for the beer to flow.
    
   OR 
   Gas shut off valves may be closed or partially closed.
   
   
3. The gas pressure may not be set properly or your tank may be empty.  The tank level regulator should be in the green section.  Typical pressures are 14-15 psi on the beer regulator and 45 - 50 psi on the Tap regulator.
   
   
   
   

For the basics of changing a stainless steel beer keg, click here.