Why msgbox is not appearing and why items aren't being removed?

Many problems have appeared in my form.

1. I put some "msgbox" to test it. When I run the first time they appear. When I click to open the form again, the messages simply disappear, even though I had written msgbox "why??" in the first line of code.

2. We created a code to remove empty items from the combobox, but they just aren't excluded. They asked that I reversed the "for", to start from the bottom up. Didn't solve.

3. The program is unable to calculate the minimum and the average of a range, although the code is correct.

Someone, please, would be able to help me?