ISARRAY doesn't work as I expect inside a function

local $foobar[2] = ["one","two"]
test($foobar)
func test(byref $array)
	 msgbox(0,"","isarray: " & isarray("array"))
endfunc

I want to create a function that accepts as parameter both an array or a simple variable so inside this function I must test if it's an array or not.
In my example I expect to see the message "isarray: 1".   Why do I get "isarray: 0" instead?