OEM 统计datafile怎么出现负数了？这个表空间之前用掉50%左右，今天将表都truncate掉，现在出现负数了，BUG？

Select File Name Tablespace Status Size (MB) Used (MB) Used (%)
/oradata/orcl/B4SPACE_01.dbf B4SPACE ONLINE 500.000 8.812 1.76
/oradata/orcl/CMRSPACE01.DBF CMRSPACE ONLINE 5,120.000 1,118.750 21.85
/oradata/orcl/L5MSPACE01.dbf L5MSPACE ONLINE 500.000 19.438 3.89
/oradata/orcl/OFFICE01.dbf OFFICE ONLINE 100.000 3.812 3.81
/oradata/orcl/PBRSPACE01.dbf PBRSPACE ONLINE 2,000.000 45.312 2.27
/oradata/orcl/PBRSPACE02.dbf PBRSPACE ONLINE 2,048.000 868.438 42.40
/oradata/orcl/PBRSPACE03.dbf PBRSPACE ONLINE 2,048.000 861.000 42.04
/oradata/orcl/QHTDATA01.DBF QHTDATA ONLINE 5,000.000 0.062 0.00
/oradata/orcl/VIPSPACE01.DBF VIPSPACE ONLINE 5,000.000 -2.562 -0.05
/oradata/orcl/VIPSPACE02.DBF VIPSPACE ONLINE 5,120.000 5.000 0.10
/oradata/orcl/clt_stats01.dbf CLT_STATS ONLINE 100.000 11.625 11.62
/oradata/orcl/magspace01.dbf MAGSPACE ONLINE 500.000 9.188 1.84
/oradata/orcl/npm01.dbf NPM ONLINE 1,000.000 94.375 9.44
/oradata/orcl/sysaux01.dbf SYSAUX ONLINE 440.000 403.312 91.66
/oradata/orcl/system01.dbf SYSTEM SYSTEM 500.000 498.562 99.71
/oradata/orcl/temp01.dbf TEMP ONLINE 267.000 266.000 99.63
/oradata/orcl/undotbs01.dbf UNDOTBS1 ONLINE 1,115.000 59.125 5.30
/oradata/orcl/users01.dbf USERS ONLINE 5.000 0.438 8.75