I haven’t tried methylphenidate mainly because of a Gene test that I did, which showed which medications would be more compatible with my genetic profile; methylphenidate was listed as being not as effective as amphetamines. I’ve had a great response to them some of the time, so I assumed methylphenidate wouldn’t work for me. I’m currently in the process of titrating my dosage. I haven’t found any other common denominators which could be causing this, aside from long-acting amphetamines. I will ask my doctor about it nonetheless.