A Fun Date Conversion Issue

So, I've been programming for a number of years.
Finding some intricately asinine issues w/ ASP.NET and VB.NET as I learn them.
How about this one:


<%=DateDiff(DateInterval.Day, Convert.ToDateTime(String.Format("{0:d}", StrTxtBox.Text)),FirstWeekOfYear.Jan1)%>
The issue is not Date1
The issue is Date2.
No kidding.
I had to String.Format Date1 for some odd reason, even though I'd already validated it.  And, yes, I tried to parse and convert Date1 ... but I kept gettting the typical "Argument 'Date2' cannot be converted to type 'Date'." error.
(Did you catch the copy & paste?  I didn't edit it from my existing error, but Date2 should be Date1.)
Yeah, that's the error I'm getting now with the above ...
"Argument 'Date2' cannot be converted to type 'Date'."
D ...