Adding external WMS via cesiums default proxy

I have an external WMS url to add it in cesium application. I am using tomcat server to host the cesium application. Below is my code
new Cesium.WebMapServiceImageryProvider({

url : ‘’,

layers : ‘zzzzz’,

proxy : new Cesium.DefaultProxy(’/proxy/’),

parameters : {

transparent : ‘true’,

format : ‘image/png’




Do i need to do anyother additional configuration?

Nothing else required. Are you having a problem?

Yes My WMS is not getting added to the map.

Are there any error messages in the console?