ESQL/C Errors

Can anyone help me with a problem I am having with Informix ESQL/C for Windows? Below are three lines of ESQL/C source which preprocesses OK under Unix but cause errors under Windows NT. The following source line (356): EXEC SQL CONNECT TO :db_name AS :conn_name WITH CONCURRENT TRANSACTION ; causes the following errors: esqlc: "ifx.ec", line 356: Error -33200: Invalid statement on symbol 'CONNECT'. esqlc: "ifx.ec", line 356: Error -33051: Syntax error on identifier or symbol ':'. ----------------------------------------------------------------------- The following line (381): EXEC SQL SET CONNECTION :conn_name ; causes the error below: esqlc: "ifx.ec", line 381: Error -33051: Syntax error on identifier or symbol 'CONNECTION'. ----------------------------------------------------------------------- The following line (401): EXEC SQL DISCONNECT :conn_name ; causes these errors below: esqlc: "ifx.ec", line 401: Error -33200: Invalid statement on symbol 'DISCONNECT'. esqlc: "ifx.ec", line 401: Error -33051: Syntax error on identifier or symbol ':'. The parameters after the ':' symbols are declared host variables e.g.: EXEC SQL BEGIN DECLARE SECTION; PARAMETER char* db_name ; PARAMETER char* conn_name ; EXEC SQL END DECLARE SECTION;