COMSOL MULTIPHYSICS

I am trying to implement gas sensor using COMSOL. The structure is ready but laminar physics is not working. as soon as this physics is applied, an error message appears. pic attached for reference. can anyone help me with this. in addition to that, i want to plot the following graphs

a) Resistance vs concentration
b) Concentration and flux plots
c) Resistance vs time
d) Concentration vs time
e) Response vs time
f) Adsorption and desorption process
the designed structure and required velocity profile is also attached