Can you provide more info.
1. your web container is in a different jvm from the ejb container ?
2. if your containers (web and ejb) are located on the same subnet ? or same box ?
3. if the web container is on a different box than from your ejb container host, can you ping it ( <from web-container-box>ping <ejb-container-box> } ?
Thats all i can offer for now. If you cannot ping, it is possible that your webcontainer and your ejb-container are on different subnets.
Maybe I am ignorant. But give it a go.