So I've switched to Gambatte which helped me stop manipulating a Rattata, I am going to practice more now but I was wondering I always pick up the Potion before the manip spot, does picking it up not allow me to do the manip?

I got 8 Pokeballs at the mart and I save as soon as i enter route 2 but i still manip a Rattata.

I'm on BGB trying to manip the Pidgey on Route 2 but whenever I try and do it I always manip a Rattata instead, please help!