Help! Error -261

Can anyone explain what causes this error? It occurs when I try to create a temporary table inside a RDS 4gl program. I use SCO Unix 3.2v4, RDS 4gl 4.11, and Online 5.01. Here's the error message: SQL statement error number -261. Cannot create file for table (richp.tbaaaa062392). SYSTEM error number -113. ISAM error: the file is locked. "richp" is the name of the creating user; tbaaaa062392 is the name of the temporary table (the program creates a new name using the unix utility tmpnam for each one). What is getting locked here? I'm not creating any unix files, as far as I can tell, and the v5 Online manual says that temporary tables are created somewhere in dbspace, though they're not held in system tables. Can anyone please help me?