My error message is as follows:
However, I've run into Conversion Problems enough that I'm going to make a guess.
I'm assuming that the value you're getting from the form is a String, because all data on the form are strings (view souce and prove it to yourself).
When you try to shove a String into a Date, you get an exception, like trying to pound a square peg into a round hole.
To get around that, simply convert the String to a Date, then you're done.
You can use SimpleDateFormat to parse the string, then convert from Calendar to Date (if you don't know how to do any of this, Google is your friend).
Something to note: [bold]always[bold] assume that any data you get from the user is going to be bad, and take the appropriate precautions (exception handling, reject bad dates, whatever), or expect to be hacked. NEVER EVER set yourself up for SQL Injections!