What version of Visual Studio and Visual Assist are you using?
I got the same tooltip, but when I press enter, it accepts the listbox using VS2012 and VA2001.
Can you please try if you are able to reproduce the problem using the following, very simple sample?
void func(int apple)
{
int orange;
func
}
Just type ( after func and then press enter. I'm wondering if the source code or the settings play a role here.