地图代数 工具计算指数报错

地图代数计算指数是报错，表达书为Power("E:\003 项目\XKY_SPJ\DYS4_R.img" * "E:\003 项目\XKY_SPJ\DYS4_K1.img" * "E:\003 项目\XKY_SPJ\DYS4_LS.img" * "E:\003 项目\XKY_SPJ\DYS4_C.img",0.25)；计算报错，报错信息是
ERROR 000539: Runtime error 
Traceback (most recent call last):
  File "D:\Program Files (x86)\ArcGIS\Python\ArcGIS10.1\Lib\warnings.py", line 29, in _show_warning
    file.write(formatwarning(message, category, filename, lineno, line))
AttributeError: 'geoprocessing sys.stdout object' object has no attribute 'write'