check to see if you have 12v to the small post wire on top of the solenoid when you turn key to on. Pull the wire off and test wire to ground while someone cranks
Note that you will only have 12 v power available at the starter side of the starter relay when you are cranking the engine. You can check the relay by putting a meter across the 12 v in and 12 v out terminals, with the wire to the starter disconnected. If connected to the battery it will show 12 volts, when the key is in the start mode.
Sounds like the problem may be elsewhere, and perhaps on the circuit from the ignition switch.
Troubleshoot your ignition switch. If the trigger wire is not sending 12V when the key is turned, that is the most likely cause. I am assuming you can cross the solenoid posts and crank the car? You can also disconnect the trigger wire from the smaller post and use a jumper wire to put 12V on the small post from the battery. If either, or both of those work, that is a good indication that the problem is in the ignition switch.