I have 10+ SMB6004 cameras. Works great. Lenses M13VG550 and TV2710D-MPIR.
I buy ir backlight IRLAB LIR-CB88 and few cheaper from ebay.
All cameras can't see infrared light.I direct the IR projector to the camera and a very low light is seen. Try with other cameras (analog and Hikvision DS-2CD2T25FHWDI8) - light is very bright.
Why? SMB6004 have Auto (ICR), firmware is last (3.08).