Vamsi ,
Make sure your ant path is set properly.
Under Environment Variables, create new ANT_HOME, system variable with the respective physical file paths as the value.
Example:
Variable: ANT_HOME
Value: C:\Development\apache-ant-1.9.2
Next I add the following values to the Path system variable in Environment Variables:
For me its a mixture of android , java, Ant ,
Since you have android, java setup already , go with only ant
%ANT_HOME%\bin;
%JAVA_HOME%\bin;%ANT_HOME%\bin;%ANDROID_HOME%\platform-tools;%ANDROID_HOME%\tools;