With certain input file types the output image is completely black, even if a lossless compression is applied. This happens because MrSID images are 8-bit images. This effect can be seen when converting 16-bit (or other non-8-bit) images to the MrSID image format.
Manually adjusting the dynamic range may help. You can use the histogram in the GeoExpress color balancer to preview and adjust the output image so that the entire dynamic range of the image is visible.