Accessing controls with its id is not a good idea. If you move/delete/add control in your tab, the id may change.
If you want to show it only on a specific category, you can do it with a pdm_if
<pdm_if "$args.category.sym" == "CategoryName">
<pdm_macro name=dtlCheckbox attr=attribute hdr=header>
</pdm_if>
And if you plan to show it on several category, you can add an attribute to your category : z_showSpecificCheckbox, integer.
And
<pdm_if "$args.category.z_showSpecificCheckbox" == 1>
<pdm_macro name=dtlCheckbox attr=attribute hdr=header>
</pdm_if>