Method Error 500 and 12030

[Gary L]

I'm attempting to implement cascading drop downs using AJAX. I am collecting
the data from a database adding the values to CascadingDropDownNameValue and
returning the values array. The first time I run it I get a method error 500
in the parent drop down and a method error 12030 in the child. Subsequent
runs show a 12030 in both. Googling this has proved fruitless, any ideas?

Thanks,

Gary L.