Your original approach is more efficient but that is your choice of course. Every time you load the main form your tab control loads the other forms whether you will need them or not. Since you have more than 2 list items in your combo I suspect you will have as many loaded forms as there are list items. Will you notice a big difference in performance today? Perhaps not but let's see what happens down the road when you get a lot of records.

Your major issue was that you were trying to use the wrong property to set which subform was loaded. The property sheet can guide you for next time, although what is shown there is most often a descriptive term rather than the actual property name. Usually it's just a matter of removing spaces between words.