Unable to import module es

My name of the handler on console is es.handler.
With S3-Lambda-ES I am getting the following error

START RequestId: d6b5b2d1-672d-11e6-a9ef-1dccc79021cb Version: $LATEST
**Unable to import module 'ES':** Error at Function.Module._resolveFilename (module.js:325:15) at Function.Module._load (module.js:276:25) at Module.require (module.js:353:17) at require (internal/module.js:12:17) at Object. (/var/task/ES.js:19:18) at Module._compile (module.js:409:26) at Object.Module._extensions..js (module.js:416:10) at Module.load (module.js:343:32) at Function.Module._load (module.js:300:12) at Module.require (module.js:353:17)

I am clueless, any inputs will be appreciated.

The report identifies the es.handler entry point and an import failure in ES.js at line 19; begin by inspecting that file and the dependency referenced there. Reproduce the S3-Lambda-ES deployment, then verify that Lambda can load the handler without the “Unable to import module” error.

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