[Observium] observium alert not working

Hi Observium Team, BDCOM is one of the big ISP and IP Telephony Service provider in Bangladesh I am deploy it in my IP Telephony network. I am follow your documentation step by step. I am add host and view all the graph its working fine. But I can not see any alert message. I am configure it but its not working. Could you please help me how can i get specific alert like my ram memory 75% use, Processor 60% use. I need customised alert to monitor my netwrok device properly . I am wating for your valuable feedback.