Issues with distinguishing "Content" and "String"

I wanna change the texture of the skybox using TweenService
here’s the target:

local daySky = {
	SkyboxBk = "rbxassetid://9544505500",
	SkyboxDn = "rbxassetid://9544547905",
	SkyboxFt = "rbxassetid://9544504852",
	SkyboxLf = "rbxassetid://9544547694",
	SkyboxRt = "rbxassetid://9544547542",
	SkyboxUp = "rbxassetid://9544547398"
}

But when I want to execute it, it returns this error:


How do I fix this issue, and if I can’t, what are the alternate to this?