The reason why monitor can see camera's image but they are black&white and not colorful in daytime is because cameras may be incompatible with DVR.
Therefore, if you face this issue,
1. If both DVR and all cameras are from us, please tell us both DVR and camera's model number.
You can find model of DVR at bottom of recorder such as DH81NK
The camera's model is on its white label such as C11BE.
2. If DVR or camera is not from us, please tell us DVR or camera's brand and model number so that we can search its specification online to see if they are incompatible with our device.
Please remember tell us both brand and model number.