I'm having a problem setting dates in a 2.0 User Event Script.

I have a custom date field on a Sales Order and I need to set the date. Here's a simple code snippet:

must_ship = Date('10/04/2017');
orderRecord.setValue({
                    fieldId: 'custbody_must_ship_date',
                    value: must_ship
});

The error returned is "The field custbody_must_ship_date contained more than the maximum number ( 10 ) of characters allowed."

This error leads me to believe I should be sending a string. 10 characters holds a date perfectly. However, If I try setting a string instead of a Date object, I get this error: "You have entered an Invalid Field Value 10/04/2017 for the following field: custbody_must_ship_date"