SAVE_TEXT problem - it can't lock??

Hi, ALL.

I use the Function Module 'SAVE_TEXT' in my Zprogram.

It update the Sales long text in MM02.

When a user is in MM02, 'SAVE_TEXT' the Function Module doesn't return error message.

I think it's a LOCK error, but it's not.

Do I need to check LOCK before call function 'SAVE_TEXT' in Zprogram??

If you know that, please let me know.

Regards.

Rie.