Picking a random member of a Type List

Actually speed isn't important in this case here is my function.

It says Compile Error: Unable to convert from 'boss_fragment' to 'Int'

Function choose_cell()
	Local member%=Rand(1,CountList(boss_fragment.boss_fragment_list))
	Local counter%=0
	For Local i:boss_fragment=EachIn(boss_fragment.boss_fragment_list)
	 counter:+1
		If counter=member
			Return i
			Exit
		End If
	Next
End Function