confusing destructor

umm, i was under the impression that this should output "destructor was called"?

Type Ttest
	Method New()
		Print "constructor was called"
	End Method
	
	Method Delete()
		Print "destructor was called"
	End Method
End Type

Local a:Ttest = New Ttest
a = Null

the reason i ask is that i wanted to call the destructor from another class, so i was kind of hoping that something like this would work :

Type Ttest
	Method New()
		Print "constructor was called"
	End Method
	
	Method Delete()
		Print "destructor was called"
	End Method
End Type

Type Tkill
	Method killReference:Ttest(tmp:Ttest)
		tmp = Null
	End Method
End Type

Local a:Ttest = New Ttest
Local b:Tkill = New Tkill
b.killReference(a)

but no luck with that either, i am sorry if this has been covered before, i've been reading and reading, got a feeling it's got to do with the GC and passing references - but i just don't get it...

i am a OOP newbie, so please bear with me for asking silly questions....