Hello Paul
The plane attribute does not control which tab an edit control appears on, although it would appear to be so from the control editor. This is actually a deficiency in the control editor, as it does not offer access to change the tab number but only for a plane number.
The option to set the tab number is only available by right clicking on a control, you will see there is an option to "Associate with a Tab" and you can select the appropriate tab.
Regards
Al