Help!!

I ran a simple flow simulation of flow inside a rectangular channel; flow simulation went fine with no error, and I was able to do a Surface Plot of shear stress on the bottom plate of the channel.

I am now trying to obtain those shear stress values at certain coordinates on that bottom plane and export it to excel, so I did Point Parameters and chose a few points on that plane. However an error message came up: "No parameters can be evaluated. Please check selected points or parameters." -- even though clearly the Surface Plot shows some finite values of shear stress.

Any idea why this occurs / what the solution is?

Did you try using the Export Result tool, all the way at the bottom of the feature tree? You will get a .txt file of coordinates and values that you can import into Excel using the simple text tool.