protected override bool not working fine

[ProH90]

I am developing an application in visual studio 2012. in MainClass

 
public static bool shrtcutky(System.Windows.Forms.Keys e, System.Windows.Forms.Form myform, System.Windows.Forms.ToolStrip tolbr, String db, String cmd, String ky, String[] arr)
    {
        switch (e)
        {
            case System.Windows.Forms.Keys.F4 | System.Windows.Forms.Keys.Control:
                {
                    myform.Close();
                    return true;                                               
                }
            case System.Windows.Forms.Keys.F3:
                {
                    SetCancelBtn(myform, tolbr);                        
                    return true;
                }
            case System.Windows.Forms.Keys.F5 :
                {
                    return true;
                }
            case System.Windows.Forms.Keys.F6 :
                {
                    return true;
                }
            case System.Windows.Forms.Keys.F7:
                {
                    System.Windows.Forms.Form FViewAll = new FViewAll(myform, tolbr, db, cmd, ky, arr);
                    FViewAll.ShowDialog(myform);
                    getLan(FViewAll);
                    return true;
                }
            case System.Windows.Forms.Keys.F8:
                {
                    SetFirstBtn(myform, tolbr, db, ky);
                    return true;
                }
            case System.Windows.Forms.Keys.F9 :
                {
                    if (Int32.Parse(tolbr.AccessibleDescription) > 1)
                        SetPrvBtn(myform, tolbr, db, ky);
                    return true;
                }
            case System.Windows.Forms.Keys.F10:
                {
                    if (Int32.Parse(tolbr.AccessibleDescription) < Int32.Parse(tolbr.AccessibleName))
                        SetNextBtn(myform, tolbr, db, ky);
                    return true;
                }
            case System.Windows.Forms.Keys.F11 :
                {
                    SetLastBtn(myform, tolbr, db, ky);
                    return true;
                }                    
        }
        return true;
    }

}

In Calling Form

 
 protected override bool ProcessCmdKey(ref Message message, Keys keys)
    {            
        MainClass.shrtcutky(keys, this, Toolbar, db, cmd, ky, arr);
        return base.ProcessCmdKey(ref message, keys);
    }

It works sometimes and sometimes doesn't .
Example : When i use the F8 key it works well,but When using the F9 key it do nothing . when i try to debug it works well.