Error in Expression

[Ezther1997]

I have the following expression but keep getting the same error. As far as I can see there are enough brackets in place so I am really lost as to how to resolve this error.

if([Actual Delay Window]=<15, RGB(124, 248, 62), if([Actual Delay Window] > 15,RGB (255, 255, 0), RGB (192, 192, 192)))

[Or]

if([Actual Delay Window]<=15, RGB(124, 248, 62), if([Actual Delay Window] > 15,RGB (255, 255, 0), RGB (192, 192, 192)))

[Ezther1997]

Thank you this works!