Marker are unitless!!!!!!! in Mathcad Prime??

That is great trying to do a 2D plot, X-axis with unites, Y-axis is unitless, when I try to add vertical marker, I get the error massage (Marker are unitless, add unites next to the trace definitions).

Well the trace itself coming from equation, I really shouldn't get this message.

Any advise.

Thank you in advance.