A very interesting question?

This is a very interesting problem cause the problem line isn't working and it doesn't give a error it automatically changes the color and the selected object value isn't even the button. I would appreciate any help.

local selected = script.Parent.Parent.selected.Value
    
local basecolor = Color3.fromRGB(177, 177, 177)
        
          
        
if script.Parent.name.MouseButton1Click and selected == nil then -- the problem is this if and then
        
    wait()
        
    selected = script.Parent
        
    selected.BackgroundColor3 = Color3.fromRGB(177, 177, 233)
        
   else
        
    selected.BackgroundColor3 = basecolor
        
    wait()
        
    selected = nil
        
    selected.BackgroundColor3 = Color3.fromRGB(177, 177, 233) 
end

On line 21, you set your variable to nil and then try to set the backgroundColor3 to it on line 23. Simply don't set it to nil, or change your variable names if they're conflicting.