Error in MATLAB when connectiing with java

I’m using Matlab 7.12.0 (R2011a) and Netbeans IDE 8.0.1. I use matlabcontrol API to connect Matlab and java application. When I try this example :

MatlabProxyFactoryOptions options = new MatlabProxyFactoryOptions.Builder().setUsePreviouslyControlledSession(true).build();
MatlabProxyFactory factory = new MatlabProxyFactory(options);
MatlabProxy proxy = factory.getProxy(); 
proxy.eval("disp('hello world')");
proxy.disconnect();

the error message Undefined variable “matlabcontrol” or class “matlabcontrol.MatlabClassLoaderHelper.configureClassLoading” comes in matlab.

How should I solve this problem? Please guide me.

Thanks in advance.