> Markup. Checkbox is disabled in code-behind based on a business rule.
```
<ajax:ToggleButtonExtender runat="server" ID="tbePrimaryDept"
TargetControlID="chkPrimaryDept"
CheckedImageUrl="Images/yes.PNG"
UncheckedImageUrl="Images/no.PNG"
DisabledCheckedImageUrl="Images/yes.PNG"
DisabledUncheckedImageUrl="Images/no.PNG"
ImageHeight="25" ImageWidth="57">
</ajax:ToggleButtonExtender>
<ext:CheckBox ID="chkPrimaryDept" runat="server" />
```
```
<ajax:ToggleButtonExtender runat="server" ID="tbePrimaryDept"
TargetControlID="chkPrimaryDept"
CheckedImageUrl="Images/yes.PNG"
UncheckedImageUrl="Images/no.PNG"
DisabledCheckedImageUrl="Images/yes.PNG"
DisabledUncheckedImageUrl="Images/no.PNG"
ImageHeight="25" ImageWidth="57">
</ajax:ToggleButtonExtender>
<ext:CheckBox ID="chkPrimaryDept" runat="server" />
```