question: Document Express capability is required to use this method/property....

Hi, dear sir/lady,

We are a software company and developing a image scanning software. I tried to run the example from the Lead tool document in the following, and want t o use the default config of the scanner.But I always get a exception when program hit method of theTwain.FindFastConfig(). The exception is : Document Express capability is required to use this method/property. What is reason causing that? Thanks for your help.

                   //theTwain.Acquire(LEAD.Drawing.Imaging.Twain.Twain.UserInterfaceConstants.None);

theTwain.OnFastConfig += new LEAD.Drawing.Imaging.Twain.Twain.FastConfigDelegate(FindFastConfigEvent);

                   theTwain.EnableFastConfigEvent = true;

                   theTwain.UserFastConfigsCount = 0;

                   theTwain.FindFastConfig(@"c:\Twain", LEAD.Drawing.Imaging.Twain.Twain.UserInterfaceFastConstants.Show, LEAD.Drawing.Imaging.PixelFormatConverter.Convert(1), 0);

                   MessageBox.Show("FindFastConfig method was successfull");

                   MessageBox.Show("Result Scan Configs count = " + theTwain.FastConfigsResultCount.ToString());

                   MessageBox.Show("Transfer Mode = " + theTwain.FastConfigsResult[0].TransferMode.ToString() + "\n" +

                         "File Format = " + theTwain.FastConfigsResult[0].FileFormat.ToString() + "\n" +

                         "Buffer Size = " + theTwain.FastConfigsResult[0].BufferSize.ToString() + "\n" +

                         "Required Time = " + theTwain.FastConfigsResult[0].RequiredTime.ToString());

                   MessageBox.Show("Transfer Mode = " + theTwain.BestFastConfig.TransferMode.ToString() + "\n" +

                         "File Format = " + theTwain.BestFastConfig.FileFormat.ToString() + "\n" +

                         "Buffer Size = " + theTwain.BestFastConfig.BufferSize.ToString() + "\n" +

                        "Required Time = " + theTwain.BestFastConfig.RequiredTime.ToString(), "Result Scan Configurations...");