Field shows in wrong tab in portal

[enquirerfm]

I've set up a portal with several tabs. There's a field which shows up under several tabs which is an irritation. Can't understand why. It seems to be related to its position in the tab where it is supposed to show - it is near the bottom. If I move the field up (problem is there's not much room) then it disappears. What am I missing?

[Vaughan]

Cut the field and paste it back into the tab control, and make sure it's within the control boundaries.

[enquirerfm]

Tried this - tried sending backwards etc etc. None of it works.