JavaScript HTTP error when http service proxied by NAM

Hi everyone, 

I made a proxy service for an HTTP service via NAM, and the application shows me a HTTPS error when I try to download the page javascript files. 

I think something in the HTTP rewrite is not working as expected. 

Here is a screenshot from the error: 

I had read that NAM by default changes the HTTP headers to HTTPS headers, but I don't think that actually works for our specific case. 

Please if somebody have some idea what's happening I'll be so thankful.