VIP Frame Reader

Hello, after read a lot of information about Nios 2 and fpgas, my project is almost finished but I still having problems with the FrameReader.

My project takes a frame from an Avalon ST video and stores it in ddr memory, after that one custom instruction perform a some modifications over the frame in memory and finally the FrameReader should read the frame from memory and give it to one Clocked Video Output connected to NEEK LCD.

The frame is correctly stored in memory but when I try to show it in the LCD, the frame is showed for a moment and after that I got a black-screen. May anyone help me?.

The FrameReader video output is connected directly (without any buffer) to the Clocked Video Output and the initialization code is:

    // Frame Select
    IOWR(ALT_VIP_VFR_0_BASE, 3, 0);
    // Frame 0 Base Address
    IOWR(ALT_VIP_VFR_0_BASE, 4, &P);
    // Frame 0 Words
    IOWR(ALT_VIP_VFR_0_BASE, 5,  800*480);
    // Frame 0 Single Cycle Color Patterns
    IOWR(ALT_VIP_VFR_0_BASE, 6,  800*480);
    // Frame 0 Width
    IOWR(ALT_VIP_VFR_0_BASE, 8, 800);
    // Frame 0 Height
    IOWR(ALT_VIP_VFR_0_BASE, 9, 480);
    // Frame 0 Interlaced
    IOWR(ALT_VIP_VFR_0_BASE, 10, 3);
    // start Frame Reader
    IOWR(ALT_VIP_VFR_0_BASE, 0, 1);