Checking if object has custom attribute

I've got a recursive deep-copy function to create new instances of objects. To improve my function's capabilities I want to put some kind of <noCopy> custom attribute on some values within my object to prevent them from beeing copied

an object to be copied may look like this:

public Class CDatabase
    public var1 as double
    private var2 as CSomeObject
    <noCopy> private var3 as double
    <noCopy> private var4 as CSomeObject
    ...
end class

my recursive function looks like this:

public shared Function Copy(originalObject as Object) as Object

    if originalObject = nothing then
         return nothing
    end if

    if Attribute.IsDefined(originalObject.GetType, GetType(NoCopy)) 'This does not work
         return nothing
    end if 

    ~ do other recursive stuff ~

    return cloned object
end function

my attribute is defined as followed:

<System.AttributeUsage(System.AttributeTargets.All)>
 Public Class NoCopy
    Inherits System.Attribute
 End Class

and I call my clone function like that:

public Class Example

    dim original as Database
    dim clone as Database
    clone = original.Copy

    'This one returns true
    Dim test As Boolean = Attribute.IsDefined(original.GetType.GetMember("var3")(0), GetType(NoCopy))  

end class

when I try to get the attributes of originalObject I always get a false return value. But when I do it by referring directly to the object I get a positive result.