ArcGIS中栅格属性表的编制问题

我有一个python脚本,可以生成光栅的属性表。这将遍历我拥有的所有浮动光栅,将它们转换为int,然后生成一个属性表。

在前3个光栅上,我收到一条警告信息,

Value range for c:\raster2 exceeds 100000 and number of unique values exceeds 500.
Please use BUILDVAT if a VAT is required.

但会生成一个属性表。然而,在这之后,程序崩溃了,我不知道如何修复它。这是打印到屏幕上的错误消息:

Value range for c:\raster2 exceeds 100000 and number of unique values exceeds 500.
Please use BUILDVAT if a VAT is required.
Traceback (most recent call last):
  File "LEED_raster_attribute.py", line 50, in <module>
    make_attribute( 20, 'C:\\Analysis\\Raster_Distances\\city' )
  File "Raster_attribute.py", line 40, in make_attribute
    gp.BuildRasterAttributeTable_management(outRaster)
arcgisscripting.ExecuteError: ERROR 000521: The number of unique values exceeds the limit.
Failed to execute (BuildRasterAttributeTable).

谢谢。