Pitstop 11: Check document colors

Good day everyone,

Currently I am using pitstop v11, but I can't get the color check as desired.

What I want is
Check document for color
Approved colors; Black and Gray.
Disallowed colors; C,M,Y and RGB.

Only problem I have is
With the preflight;
Document contains colors other than tints of the following color;

• Black (checked)
• Image or not black (checked)

I get an error message for NChannel color black. But this is good and prints well with me. So I do not want him showing it as error message.

So, how can I use my check colors in this way, he doesn't shows this as an error anymore!?