Ignition lock cylinder
 

We're replacing the ignition lock cylinder in a 1990 Honda Civic DX. Got the old one out by putting the key in the accessory position and pushing the release button and it came out. We can not get the new one to go back in. Have tried putting the key back into the accessory position and pushing the button down before inserting the new one. It goes in, but it won't go all the way. What's the trick? Thanks for your help.