Cursor not found

I hope that you will be able to help me. I am using Informix-SQL and Informix 4GL 7.20.UD1 and I have come across an error... or at least I believe it to be an error. I have a test program that looks like the following. database tis main define str char(200), up_str char(200), y integer let str = "select * from account for update" prepare ex_str from str declare x for ex_str let up_str = "update account set account_num = ? where current of x" prepare ex_up_str from up_str begin work open x fetch x into y execute ex_up_str using y commit work end main Please ignore any syntax errors. Essentially accounts has one column that is an integer. This database has transaction lgging turned on, but when it is executed it gives a: Cursor (x) not found. error message. Any suggestions?!