volatile declaration problems

[Skatanic]

I am using threads to update an STL multimap holding my data. Since they will be concurrent I am trying to declare the multimap as volatile. However this produces a compiler error on the line when I call the insert function for the multimap. When I remove that keyword, it compiles fine. My question is if there is a way to declare it volatile and still use the multimap or if not declaring it volatile will harm my program in any way?

Thanks,
Skatanic