Storage.Shared does not work...

[Browsable(true), Category("My Cat"), DefaultValue(""), WebPartStorage(Storage.Shared),FriendlyName("MyName"), Description("Description")]

public string Prop

{

get

{

return _prop;

}

set

{

_prop = value;

}

administrator sets the property eerything works fine , but it is empty for end users!!! I thought

WebPartStorage(Storage.Shared) makes it only set by admin and shared between all uses.
What am I missing?

Thanks a lot