Dynamically loading unmanaged OCX in C #

I have ocx created in VC ++. If it is loaded statically, it works fine, but when I load it dynamically from the assembly, it gives an exception.

    public Assembly assembly;

    public Form1()
    {
        InitializeComponent();            
       assembly = Assembly.LoadFile(Application.StartupPath + "\\abc.ocx");

    }

he gives the following exception. The module is expected to contain an assembly manifest.

(Exception from HRESULT: 0x80131018)