Oracle Database Discussions

hi
so many times i have ask this question in forums but i didn't found any good workaround for this problem. i want to shrink my datafile but i m getting error because of HWM shifed to very high value plz. see the below output of my db and suggest me the workaround.

FILE# tablespace_name #Meg #Used #Free %Free
---------- ------------------------------ --------- --------- --------- --------- --------- --------------
7 TSMISC 6419.06 852.63 5566.44 86.72

SQL> SQL> alter database datafile 7 resize 1000m;
alter database datafile 7 resize 1000m
*
ERROR at line 1:
ORA-03297: file contains used data beyond requested RESIZE value


SQL> alter database datafile 7 resize 5000m;
alter database datafile 7 resize 5000m
*
ERROR at line 1:
ORA-03297: file contains used data beyond requested RESIZE value