Web Forms :: Start And End Time Validation Using CustomValidator

I want my Start Time and End TIme should not be equal to each other and I want the End TIme should not go beyond the Start TIme. For example:

Start Time = 8:30 AM

End Time = 8:00 AM

The above example should have an error because the End Time go beyond the Start Time.

My HTML code:

Time In:

<cc1:MaskedEditValidator ID="mevStartTime" runat="server" ControlExtender="meeStartTime"
ControlToValidate="txtStartTime" IsValidEmpty="False" EmptyValueMessage="Time is required "
InvalidValueMessage="Time is invalid" Display="Dynamic" EmptyValueBlurredText="Time is required "
InvalidValueBlurredMessage="Invalid Time" ValidationGroup="MKE" ForeColor="Red" />
<asp:TextBox ID="txtStartTime" runat="server" Text='<%# Bind("StartTime", "{0:t}") %>'

[Code] ...

Time Out:

<cc1:MaskedEditValidator ID="MaskedEditValidator1" runat="server" ControlExtender="meeStartTime"
ControlToValidate="txtEndTime" IsValidEmpty="False" EmptyValueMessage="Time is required "
InvalidValueMessage="Time is invalid" Display="Dynamic" EmptyValueBlurredText="Time is required "
InvalidValueBlurredMessage="Invalid Time" ValidationGroup="MKE" ForeColor="Red" />
<asp:TextBox ID="txtEndTime" runat="server" Text='<%# Bind("StartTime", "{0:t}") %>'

[Code] .....