Why is my if statement still running if the condition is false? asp.net

why when if(Session["StudentRep"] == null) is false the if statement still running ???????

but in the above code the if does work! why thats happening

<ItemTemplate>
            <table>
                <tr>

                    <td style="width: 200px"><%#Eval("lesDate")%> </td>
                    <td style="width: 200px"><%# Eval("lesHour") %> </td>
                    <%if (Session["StudentRep"] != null)
                        { %>
                    <td style="width: 200px"><%# (TeacherById(Eval("teacherID").ToString())).Name %>  </td>
                    <%} %>


                    <% if (Session["StudentRep"] == null)
                        { %>


                    **<td style="width: 200px"><%# StudentById(Eval("studentID").ToString()).Name+" "+  StudentById(Eval("studentID").ToString()).FamilyName%></td>
                    <%} %>**

                    <td style="width: 200px"><%# (CityName((int)Eval("CityNum"))) %>  </td>
                    <td style="width: 200px"><%# SubName((int)Eval("subID"))+ " " +SubDif((int)Eval("subID")).ToString()+" 'יח" %></td>
                    <td style="width: 200px"><%# Eval("participant") %></td>
                    <td style="width: 200px"><%# Eval("cost") %> </td>

                </tr>
            </table>
        </ItemTemplate>