As the previous replies have pointed out you should see something in the way of lights when you push the fire button. If not then the mod either isn't turned on (normally 5 quick presses of the fire button) or is not working. It is charged, right?
It could however be a problem with the electrical connection to the coil or the coil itself. Sometimes coils are duds so do try another.
At this point if it is convenient you should return to your vendor and ask for help. If this is not an option then you will have to continue to try and troubleshoot it yourself. If you have an electrical tester and know how to use it you can check the power from the mod and the resistance through various parts of the atty to find the fault.
Something's not connecting and sometimes the problem is the center pin that connects to the center pin in the mod and through the atty's base to the bottom contact on the coil. This pin should protrude from the bottom of the atty by about a millimeter or so. It has to be the lowest point on the atty's bottom. Sometimes these pins are threaded and can be adjusted with a screw driver and sometimes there is no adjustment. If the former then the adjustment would be a miniscule turn one direction or the other, depending on which direction it isn't contacting. If you are adjusting this pin be very careful to ensure that it remains the lowest point to contact the mods pin. If you by accident raise it up equal to or higher than its surrounding threaded housing then you may create a short circuit which would not be good (hence the suggestion to take it back to the vendor). If the former then there isn't much that can be done. Do make sure though that the atty's base is fully screwed onto it's tank since that would cause it not to connect too.