How to change mask in contours tool

[BrandonFeole]

Okay so I am attempting to use the contour tool. I gave it an input raster called "AlmonoNED" and an output called AlmonoElevationContours. I set the output coordinates and extent. However, every time I run the thing it fails saying it is unable to open the mask raster AlmonoStudyArea. This mask raster does not exist nor has it ever existed. More to the point, I do not see anywhere under the environments tab where I can change the mask raster. I have been trying to fix this for over an hour and have made no progress. Any help would be hugely appreciated.

[SteveLynch]

do you have a Mask set in the Analysis environment, not the tools env but the application env?

and does it exist?

[ScottWCampbell]

You, sir, are a man for all seasons. Piggybacking with specifications for BrandonFeole: Under Analysis Tab, Geoprocessing, open up "Environments" (picture of a hammer and wrench); under the Raster Analysis subsection (5th one down) the third cell is probably currently set to AlmonoStudyArea, go ahead and replace that with AlmonoNeighborhoods from the corresponding drop-down menu. Change nothing else, run the tool, and you've got your beautiful contour lines.

Thank you Steve!