No first interrupt in VPIF raw capture mode DM6467T

Out development employ VPIF Raw Capture mode of DM6467T to acquire image from CMOS Sensor.

According to the DM6467_VPIF Manual(spruer9d), after enable Channel0/1 and Channelo/1, VPIF will generate first interrupt as soon as HSync and VSync valid. According to the manual, the interrupt can be watched by query register

INTSTAT(0x01C1202C).

But when sensor ready(PIXCLK, HSync,VSync, DIN0~DIN11) and VPIF is enabled, there is no interrupts are reported to INSTAT.

The symptom is same for either 8bits or 12bits.

What's the cause? Anybody had met such condition?

Thanks in advance