Nios II System Architect Design Tutorial problem

That warning just means that the gamma correction numbers couldn't be fetched from the EEPROM. Without proper gamma correction the colours might be off a little bit but you should still see something on the screen assuming the rest of the design is working properly.

Make sure your frame buffers are populated in the correct memory. This should be achieved by making sure the heap is located in the correct memory or the memory is named appropriately. I'm not sure which is correct since I'm not really familiar with that design but I know the driver is looking to either allocate frames on the heap, or uses a hardcoded frame buffer memory name. If the heap is use (most likely) then you need to make sure whatever memory is used for the heap also has the SGDMA hooked up to it otherwise the video pipeline will not be able to fetch the image data out of memory.