Why doesn't this boolean parameter work?

[cassb]

I have a parameter that's boolean. Here is the declaration and the get/set code.

        private bool lines;

[...]

        [Description("Plot as lines [true] or as rays [false]")]
        [Category("Plots")]
        public bool Lines
        {
            get { return lines; }
            set { lines = value; }
        }

It defaults at false. When I change it to true and click OK on the indicator screen, it always resets itself back to false. How do I get this to work?? The code looks right to me and I can't find any other indicators that use a boolean parameter.