If this is a form that you have modified in the past, it may be including previous controls from previous versions of the form. The key to the control limitations is "lifetime". Try creating a new form and copying those controls you need from the old form to the new form and see if that solves your problem. I have had this problem in the past with evolving forms and was able to correct the problem with a new form.
Another solution is to split the fields between 2 forms and call the second form from the first. I developed a hospice database with a plan of care form that exceeded the control limitation. To work around the problem, half the controls are on one form and the balance on a second.
