Zonal Statistics - too many values?

[JamesHook]

I have a large polygon layer representing a few thousand fields, and raster layer with 3 land cover classes.  I would like to summarize each field with a single land cover class, and the only tool I can think of to accomplish this is Zonal Statistics.

Problem is, when I try to run Zonal Statistics, I get ERROR 999999, "Too many unique values".  What are the limitations on this tool, and is there a better way to perform this summary?

[JeffreySwain]

You may be running into the limit of unique values in a raster.  Go to the Customize > ArcMap Options  > Raster Dataset.  Adjust the 'Maximum number of unique values to render.'  The default setting is to limit the processing time, so any adjustment up will increase the processing time.

[JamesHook]

Thanks!

For others who may be interested in a solution, it also worked to reduce the number of zones in the zone feature class.  Apparently this is a combination of value raster and zone layer size.