Starter wont engage

Ok I changed my starter out from original cause it didnt work so I put in a mini starter.
I put it all the way in the trans and I turn key and it clicks like its skipping so I make sure its driven home in the trans I find its driven home. Still clicks.
Got the original working so I purt it back in and it does the same thing like it is skipping.
Im so pissed it wont turn over and the motor spins freely by hand but cant get starter to engage
I already replaced the positive and negative cables

What do you guys think it could be?