Fake Vouch appeal

Hey , i got banned bcuz sherdderbeam says my last vouch is fake , im old school pker , and this is my appeal:
i traded with sythe person: v control v my 128 for 700$ , it went smooth he went first and all , once trade was done i asked for my vouch like any1 does , he said sythe was down to him , so he told me to post something on my sig , i copyed and i did it , then today i get banned bcuz vouch is fake ? i rly didnt knew it was , pls ?