Datafile has negative value !

 Hi all,   My OS: Linux 64 bit, Oracle 10.0.2 (64 bit)

   I have a problem with my datafile.

   My USERS tablespace have 22 datafiles.

   From the OEM, I can see USERS Tablespace with informations such as:

   1. Size(MB): 68,701.3

   2. Used (MB): 45,145.9

   3. Used(%):  65.7

   4. Free: 23,555.4

   5. Datafiles: 22

   6. Type: PERMANENT

   7. Extend management: LOCAL

   8. Segment Management: AUTO

   But, when I view detail 22 datafiles, I see the datafile number 6 (6th) have some information such as:

   1. Size (MB): 3048.00

   3. Used (MB): -7021.56  ------> I don't understand why its size: negative (-) ???

   Two day ago, I truncated data from table A belong USERS tablespace (table A has about 74 million records)!

   My Alert.log no warning about size of USERS tablespace !