Banner issue

I am using SimpleShift and I am having an issue with my Banners.

1st case: Both the main and SubBanners are set with the same image. In this case, there is a flicker in both banners… meaning when I land on the page, the banner is grey, but when I scroll down through the page, my banners appear.

2nd case: If the SubBanner is not included, the home page banner is working fine, until I move to another page, the secondary page banner is grey, as expected, but as I scroll down I get the sample banner. AND when I move back to the home page, I have the flicker again.