ELMAH showed an exception with this error message. type="System.InvalidCastException" message="Conversion
from string "GR-808" to type 'Date' is not valid."...
The compare validator (below) doesn't seem to be working for this particular user (who makes lots of data entry errors).
<asp:CompareValidator ID="IssuedDateFromDateCompareValidator" runat="server" Type="Date" ControlToValidate="txtIssuedDateFromDate" ErrorMessage="Enter Valid Date (format m/d/yyyy)" Operator="DataTypeCheck" Style="z-index: 110; left: 288px; position: absolute;
...
Go to the complete details ...