ArcGIS 10 Raster Calculator Issues

I have continuous data (depth to water table) from 0 to 400 ft and I need to assign a rating based on categories (0-10 ft is a rating of 10, 10-50 ft, is a rating of 9, 50-100 ft is a rating of 8 and so on..). The problem is that raster calculator pops up a message 'map algebra error'
ERROR 000989
Python syntax error: Parsing error : invalid syntax (line 1)
Can anyone help me with the syntax I would need? Thanks in advance