Placeholders may not work when used with an EXEC procname request. IIRC your database back-end is MS-SQL. DBD::ODBC should support placeholders for that platform for normal single query statements (select, update, delete, insert), but you'll need to read the docs to see if placeholders are supported for EXEC calls. DBD::Sybase when used in conjunction with FreeTDS does not (yet!) support them.

DBD::Sybase does support placeholders both for normal queries and for EXEC calls when used with the Sybase libraries and a Sybase database.

Michael