TM4C1294KCPDT: Problem aquiring data from ADS8900, part 2

As I mentioned in previous topic, I am able to generate periodic requests for AD8900 for reading data. This is how it looks like on a scope:

No I want to read this data via uDMA, 4100 samples, 3 bytes each, So I programmed another uDMA channel for it:

Initialization:

    uDMAChannelAttributeDisable(UDMA_CHANNEL_SSI1RX, UDMA_ATTR_ALTSELECT | UDMA_ATTR_HIGH_PRIORITY |
                                UDMA_ATTR_REQMASK);
    uDMAChannelControlSet(UDMA_CHANNEL_SSI1RX | UDMA_PRI_SELECT, UDMA_SIZE_8 | UDMA_SRC_INC_NONE | UDMA_DST_INC_8 | UDMA_ARB_1024);
    uDMAChannelTransferSet(UDMA_CHANNEL_SSI1RX | UDMA_PRI_SELECT, UDMA_MODE_PINGPONG,
                           (void *)(SSI1_BASE + SSI_O_DR), (void *)ADCData1, 4100 * 3);
    uDMAChannelControlSet(UDMA_CHANNEL_SSI1RX | UDMA_ALT_SELECT, UDMA_SIZE_8 | UDMA_SRC_INC_NONE | UDMA_DST_INC_8 | UDMA_ARB_1024);
    uDMAChannelTransferSet(UDMA_CHANNEL_SSI1RX | UDMA_ALT_SELECT, UDMA_MODE_PINGPONG,
                           (void *)(SSI1_BASE + SSI_O_DR), (void *)ADCData2, 4100 * 3);
    uDMAChannelEnable(UDMA_CHANNEL_SSI1RX);

ISR:

void SSIDoneInt()
{
    SSIIntClear(SSI1_BASE, SSI_DMARX);
    uDMAChannelTransferSet(UDMA_CHANNEL_SSI1RX | UDMA_PRI_SELECT, UDMA_MODE_PINGPONG,
                           (void *)(SSI1_BASE + SSI_O_DR), (void *)ADCData1, 4100 * 3);
    uDMAChannelTransferSet(UDMA_CHANNEL_SSI1RX | UDMA_ALT_SELECT, UDMA_MODE_PINGPONG,
                           (void *)(SSI1_BASE + SSI_O_DR), (void *)ADCData2, 4100 * 3);
    uDMAChannelEnable(UDMA_CHANNEL_SSI1RX);
}

The problem is I hit a breakpoint in the ISR periodically, the SSI status shows no overrun conditions, but ADCData* arrays contains all zeroes.

What is wrong?