Unity Ml agent: 3DBall Build error

I followed the steps as mentioned in github repo. I started a new project and opened the scene of 3DBall. When I try to build it I am getting the following error

Unable to find player assembly:

Hello, i might do the same tutorial. What do you mean with "i started a new project". I have pulled the latest git version, and opened the existing scene, and it works well. However, i am stuck in training my own model.

i am talking about this tutorial: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Getting-Started.md

hi @sathyakarthik2708 , It looks like your error message got cut off or is just a really bad error message :).

Could you provide us with what version of ML-Agents you are using, version of unity, and which platform you are running on?

Thanks.