Experts i need your help

I'm backlinks expert and i have deal with many vendors my deals were done four months ago if i message any of them some people don't reply to me where am i going wrong that some people aren't replying to me? to guide me so that i can improv myself
Thanks In Advance
Regards

What kind of message are you sending them after those four months? If it's just a general follow-up, try mentioning the last placement and asking about a specific site or new order. That gives them something clear to respond to. Also worth checking whether those vendors are still active.