add 2nd Id to hyperlink asp.net 1.1

 I have a page that requires me to add a 2nd if to pull up some data from a Db that is not related to that page.  I found some code but keep getting an error on it and have not been able to figure out the solution.
<asp:TemplateColumn HeaderText="Edit">
<ItemTemplate>
<asp:HyperLink ID="lnkEdit" text="Edit" Runat="server" NavigateUrl='<%# "J3PositionIndiv.aspx?id=" + DataBinder.Eval(Container.DataItem,"intpositionId") + "&UnitID=" + DataBinder.Eval(Container.DataItem,"intUnitMobId")%>' Enabled="True"></asp:HyperLink>
</ItemTemplate>
</asp:TemplateColumn>

Input string was not in a correct format.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the ...