About Docking Conyrols

Hi,I am stuck here with docking of user control in Windows Forms. Actually there r 3 usercontrols in the 'MAINFORM'. 1>viewer-------->DockStyle.None 2>picturebox---->DockStyle.Top 3>prompter------>DockStyle.Right When I load the mainform,the prompter is docking 'TOP' instead of 'Right'.i.e it is touching the top corner where it should dock right. What may be the soln for this?