Problem with mdb data type

I'm working with an mdb database and I've got a form with a <cftextarea> field set to rich text. When I try to update the data table I'm getting the following error:

Application uses a value of the wrong type for the current operation.

It's fine with a short entry, even with a link, but when I enter a longer string, I'm getting the error. The field in the database is a memo field set to allow rich text, and I've got the data type in the update query set to "cf_sql_longvarchar". Should I be using a different data type for this? I know for the purpose of what I'm doing I should probably be using an include instead of a database field, but I'm hoping this will work for the time being until I get more familiar with CF.

Thanks in advance for any help you could offer!

Jeremy