JScript Runtime Error

I have a TestComplete v10.5 application that tests a WPF application. One line of my code runs w/o issues 90% of the time, the other 10% of the time, I get a JScript runtime error "Unable to call the method. Status: Pending". My code gets a TextBox with the FindChild method (var textBox = parent.FindChild(.....), the calls the Click method of the textBox (textBox.Click()). The line that calls the Click method is where the runtime error occurs. I have no idea what this message means or how to even begin to debug this issue. Any help would be greatly appreciated.