Need help to load standalone application from u-boot

I tried to follow the example from README file to load the HelloWorld application. But it seem cannot load the source
When I try load command:
=> loads

Ready for S-Record download …

<---- Then it got hang here.

Is it cause of it cannot find the source or not? How should I make it run? If I write myself another standalone application, where should I put this file?

Best regards,

Thang Nguyen