DataSource Controls :: Why DbType Always 'Date' Instead Of 'DateTime'

I'm using VS 2005 and SQL SERVER 2005,now i have a table with only two columns (their types: DateTime and SmallDateTime)

i key in some new records.Now I want to use GridView to retrieve that table, and use Calendar.SelectedDate as a parameter used in WHERE statement,I press "Test Query" and pop out a window "Parameter Values Editor",

here comes the problem.. how come the "DbType" is always 'Date'?After i click the list and select 'DateTime', but next time it will recover back to 'Date'I have to go to the source code find the "Dbtype" and change from "Date" to "DateTime" manually EVERYTIME~

Like This:

From:<SelectParameters>
<asp:ControlParameter ControlID="Calendar1" DbType="Date" Name="Date" PropertyName="SelectedDate" />
</SelectParameters>

To:<SelectParameters>
<asp:ControlParameter ControlID="Calendar1" DbType="DateTime" Name="Date" PropertyName="SelectedDate" />
</SelectParameters>


if i don't do this, it will lead to error:the version of sql server in use does not support datatype 'date'

It's weird that my original datatype is "DateTime" but the Dbtype is ALWAYS "Date" and lead to error everytime.