WCF Service OperationContext null

Question

I have a wcf service. I am using this class for thread safe global variables:

public class WcfOperationContext : IExtension<OperationContext> {
private readonly IDictionary<string, object> items;

private WcfOperationContext() {
    items = new Dictionary<string, object>();
}

public IDictionary<string, object> Items {
    get { return items; }
}

public static WcfOperationContext Current {
    get {
        WcfOperationContext context = OperationContext.Current.Extensions.Find<WcfOperationContext>();
        if (context == null) {
            context = new WcfOperationContext();
            OperationContext.Current.Extensions.Add(context);
        }
        return context;
    }
}

Inside my business class I have two methods:

    public async Task<...> Method1(...){
       string refID = WcfOperationContext.Current.Items["RefID"].ToString();
       Method2();
...
    }

public async Task<int> Method2(){
    string refID = WcfOperationContext.Current.Items["RefID"].ToString();
...
}

In Method1, I can get refID from WcfOperationContext. But in Method2 sometimes (not always) I am getting an error at this line:

WcfOperationContext context = OperationContext.Current.Extensions.Find<WcfOperationContext>();

because of OperationContext.Current is null.

How can I achieve this?