Problem with order of Dock->Top controls

C# WinForms: I am designing my form and I have a couple of TableLauots. so I design my first tablelayout, throw it on the panel and set Dock->Top ... then I design my second one and do the same and set Dock->Top, it goes to Top again and good, it places under the previous one that was on top...I design the third one and set its dock.top and good it is under second one which is under first one...but I dunno what is the diffrence for the forth one that when I set its dock.top, it changes the order of the other three ones and get places some where in between them, it does not get placed under the third one...any idea what should I look in to?