Interop Forms: Problem with my user control in MS Access

Question

Hi all,

I have created a user control in C# with Interop Form Toolkit. In my MS Access application I added a reference to this control. Now I have a strange problem. I can drop this control on an access form. I can change the size and the position. If I click on my control the size will changed to the original size (like VS-Studio Designer). What's the problem and what can I do?
 
Thanks.