When you push TCN button on the UFC, you have different texts populated on the right side X and Y are the last lines, you have 2 points side of it who indicate X or Y are selected. default it is X. After enter the Tacan numbers > Enter on UFC > press ON on the UFC ( right button) for enable the TACAN ( ON Appears side of Tacan numbers )
A good practice when learning with the tutorials is to get the CHUCK Guide and use it as reference ( PDF ). https://chucksguides.com/aircraft/dcs/fa-18c/, It is easy sometimes to miss a step. You can too at same time load guide on youtube. pause inside the game watch how then come back.
