This helped me get my panels to fade in, but it seems that the button get confused with its disabled colors in the process of fading in and out. i fade out my panel and fade in another, then i fade the second panel out and the first on in, but all the buttons in the first panel get activated in such a way that their colors dont get reset from disabled.
img1 shows the buttons before the fade out, img 2 shows them after fading back in. it seems the UIButton script is getting enabled before the collider so the color stays on the disabled setting.