imap_setflag_full no works!!

[ruclamo]

Hello!!

I have problems when I try to execute this instruction (using Red
Hat 8.0 or 9.0, with php 4.4.4-8.0.5 or higher).

imap_setflag_full($msg,$elmensaje,"\ANSWERED",ST_UID);

$msg and $elmensaje are valid arguments, they are OK, but I obtain the next warning:

Warning: imap_setflag_full(): supplied argument is not a valid imap resource in ...

This instruction (and other instructions related to imap) works OK on RedHat 7.2 and 7.3. Can anybody help me to solve this problem???

Thanks!!!