Thanks for providing the information. "Record not found" means that the slider did not exist. You might have imported the demo content while the rev slider is not yet active. To resolve this, you will have to make sure that the slider being assign in your above/below masthead exist. You can check it by editing your page and make sure that it is assign to the correct and existing slider.
I went ahead and installed the Slider Revolution plugin in your site. I have seen the error and I have done the steps above. I assigned the correct slider and now it is showing in your homepage.
To know more how you can add or assign sliders in your masthead, please check out this article:
You can check your homepage now.