Data Controls :: Search Data In Between Two Dates In A GridView Control

Acutally i have added a GridView on my webform and two text box's with having asp:calender extensions, button as well. I have one table in my database with column name 'Time'(datetime)  with having some dates.

I need any one can search in between the selected dates, but i am facing a problem, if i select the excat year what i have in my database table then only i get my result into the Gridview otherwise i am getting an error........

protected void btnAdminSearchDate_Click(object sender, EventArgs e)
Line 838: {
Line 839: DateTime dt1 = Convert.ToDateTime(FromDate.Text);
Line 840:DateTime dt2 = Convert.ToDateTime(UptoDate.Text);
 
 My ASPX page code for that part is as follows...

<div style="position:relative; right:0px; "> <asp:Label ID="Label4" runat="server" Text="From" ForeColor="#E68A00" Font-Size="Larger" Font-Bold="true"></asp:Label> <asp:TextBox ID="FromDate" Height="35px" BorderWidth="2px" runat="server"></asp:TextBox>

[CODE].....