This appears to be a bug in 7 and (slightly different) 8.

Create a new form and drop a textbox on it. Set the value property to ={} and put this code in the InteractiveChange() event:

if type('this.value')='U'
wait window nowait noclear 'This.Value is Missing! '+time()
else
wait window nowait noclear transform(this.Value)+' '+time()
endif

Type in today's date with a 4 digit year and watch as you type each character. When you type in the 3rd character of the year, you'll notice that "This.Value" does not exist.

Works in 6, doesn't work in 7. In 8, it works if the .Value property has a date in it initially, but not if it's empty.

Mike