Drag & Drop functionality

In my routes I have many custom made valves thatautomatically config to the pipe size. I use the drag and drop allthe time. Sometimes when I drag an item from the routing sub folderit does not display. Eg I am moving the mouse and it is not showingthe dragged item. Most of the time it does and the system worksgreat, but on the odd occasion when it does not, I have to do manythings, exit route, enter route, drop one in space then try anddrag another ( such that the first one might be chached ) some ofthese work, some of these don't.

Any ideas as to what is going on?

Thanks
Stu
SolidworksRouting