DPlot

I am receiving "Critical error converting image to 24 bits; cannot continue." message from the Bitmap to 3D Plugin. Windows 7 properties says the file is 28.2MB, Dimensions 3538 x 4193 (Width x Height) 150 dpi, Bit depth 16, Uncompressed, Resolution unit 2. This is a greyscale (x-ray) imag...