ERROR 999998:Unexpected Error.

<P>在做图像获取栅格边界时，arcgis9.3中工具 greaster than equal 出错</P>
<P>Executing: GreaterThanEqual F:\f11_6.tif\Band_1 0 F:\Greater_f11_1<BR>Start Time: Fri Jan 15 16:38:44 2010<BR><FONT color=#f70938>ERROR 999998: Unexpected Error.<BR></FONT>Failed to execute (GreaterThanEqual).<BR>End Time: Fri Jan 15 16:38:44 2010 (Elapsed Time: 0.00 seconds)</P>
<P>谁知道这是什么原因？等待高手解决 ····</P>