Support Questions

A little while ago, I asked a friends of mine if they wanted to do a duo in the bottom lane with me as support and them as the adc. They picked Ashe and I picked Zyra, hoping that the poke would help drive my enemies out of lane. That part did work but whenever I would try to help my adc push by autoing minions (not last hitting), but every single auto-attack, I would het the danger ping. I asked the adc in the chat what was going wrong and they complained about my autoing and told me they wanted the farm. I asked her a bit more and she said I was stealing farm but I look up to the top right corner of my screen and surprise, I have 2 cs. So that brings me to the question, what was I doing wrong? I was not last hitting or taking farm, but when I step near the caster minions with the minions on full hp and auto, I got the ping... WHAT WAS I DOING WRONG?? I was hoping that anyone could possibly share the answer with me. Thank you and good luck in ranked.