Shifter button Doesn't push in

After starting the car the automatic shifter button will not push in and shift from park into any gear. When we put it in Nutural then start the car you can shift it. What would cause this problem and how would someone fix it?

Welcome to the forum jcrance. I don't know what year your car is so general information is what I'll tell you. The brake pedal must be depressed to release the shift lever. Check the voltage on both sides of the brake pedal switch when it is depressed. Do your brake lights come on with the pedal depressed? If the brake pedal switch only has one set of contacts and the brake lights come on then the switch is ok. If it has two sets of contacts then you will have to check each set to see if about 12V is on both sides of each pair of contacts when the pedal is depressed. If you find out the brake pedal switch is ok then you'll have to trace the circuit to the shift lock actuator.