Nivethika,
Is your Accumulo instance on the same machine or a separate machine as GeoServer. I haven't seen this problem when I'm trying to connect to GeoWave when on the same machine. I have however, had this problem (stumped me for a while in fact), when the GeoServer and the Accumulo instance were on separate machines. GeoServer would connect fine on the local machine but not a separate GeoServer instance. I had the same problem with GeoMesa as well.
I finally sorted out the problem for my case. First, I eliminated potential problems like firewall and network issues by pinging the machine and port and checking with netstat. Then I finally realized that in my set up (using Hortonworks sandbox), the default config files for Accumulo were referencing localhost. So from what I can tell, GeoServer would connect to Zookeeper just fine on port 2181, and it's getting the answer that Accumulo is at localhost.
Look at the Accumulo Monitor page and see what it says for the Master and Tablet servers. Does it say localhost or a FQDN? In $ACCUMULO_HOME/config, there are files called masters, tracers, slaves, monitor, and gc. If these say localhost, make sure they have an IP address or fully qualified domain name (not localhost). If they have a FQDN (like
sandbox.hortonworks.com), then you need to make sure the GeoServer machine has that FQDN mapped to an IP in the hosts file. In a sandbox they're all the same. In a cluster they can be different (and multiple) machines (and maybe they even get dynamically updated - I haven't gotten that far).
Note, that if you're using a sandbox/eval VM, you'll want to make sure it's getting a static IP.
That's how I sorted my problems with connecting GeoServer to the ZooKeeper/Accumulo box. I'm not sure if your case is the same but hopefully this helps give some ideas how to troubleshoot.
Scott