Reading the line above ^^^ am assuming these are 2 different network/providers. If that be the case, do a trace and paste here. Also check www.ipchicken.com, get the IP. After that we will check for you the BGP internet table and ascertain if the subnet provided by your ISP is propagating properly.

If above isnt true, then a filter or null route is applied somewhere along the hops/routers/firewall towards the same site./IP