COM Component - Object doesnt support this property or method

I have created a COM component and web page combination that works fine on my devlopment machine whilst debugging and once publish to the server.
However on anyone elses machine I get the error : Object doesnt support this property or method
Help
Interface File

    [Guid("E86A9038-368D-4e8f-B389-FDEF38935B2F"),
     ComVisible(true)]
    public interface IPrintXPS
    {
        [DispId(1)]
        void Print(object fileData);

        [DispId(2)]
        void RunPrint(string fileName);

        ...