unable to drop tablespace

Oracle 11.2.0.3 with two node RAC
unable to drop tablespace..

SYS@soaprd1>drop tablespace uat_soainfra;
drop tablespace uat_soainfra
*
ERROR at line 1:
ORA-01549: tablespace not empty, use INCLUDING CONTENTS option


SYS@soaprd1>drop tablespace uat_soainfra including contents;
drop tablespace uat_soainfra including contents
*
ERROR at line 1:
ORA-01561: failed to remove all objects in the tablespace specified

There are no objects in the tablespace..

SYS@soaprd1>select 'drop table '||owner||'.'||table_name||' cascade constraints;' from dba_tables where tablespace_name='UAT_SOAINFRA';

no rows selected

How to drop this tablespace ?