CDO

I'm trying to select all grid cells inside a circle around a point, but its not working.

My file (january.nc) has an area in the center that does not have any data. I need this area (approximately a circle) to be set to 0.

If I try cdo setcindexbox,0,130,178,210,258 january.nc a.nc it works, but of course it makes a square around that area.

So I tried the selcircle command, but it did not work, and always give me the message "No grid points found!"...

I appreciate any help.. Thank!