If the proxy settings are configured wrong, then Tomcat Data collection will not happen correctly as Applications Manager uses HTTP requests for data collection from Tomcat Server.
Check if you are able to access the Tomcat Server from browser in Applications Manager machine . If you are able to access the Tomcat Server from browser in Applications Manager machine , then configure the same proxy settings in Applications Manager. For example, if you have enabled "Bypass proxy server for local addresses" option in the browser, then enable the same in Applications Manager.
Proxy configuration details in browsers :
Internet Explorer :
Tools-->Internet Options-->Connections --> LAN Settings
Edit --> Preferences-->Advanced-->Proxies
In case of Tomcat Version 5.x & above you can make use of the below link from the system where Applications Manager is running to check the status of tomcat
hostname- name of the computer in which tomcat version 5.x & above is running
port- the port in which tomcat is running