It is because SendPing sends ping using
and exits immediately. At this time there is nothing in
1) Use SendAsync and update richtextbox there itself.
2) Use Send and update richtextbox depending on PingReply.
Your event will work only with SendAsync.
Occurs when an asynchronous operation to send an Internet Control Message Protocol (ICMP) echo message and receive the corresponding ICMP echo reply message completes or is canceled.