Failed to open map file

[Buggy Pine]

Hallo list,
I'm having some problems  with

ms_newMapObj("mapfile.map");

where mapfile.map is in the same directory of PHP script page (atind.php).

The warning message is:
Warning: Failed to open map file mapfile.map in
/home/mapserver/public_html/html/mapp/atind.php on line 38


I tryed also
chmod 777 mapfile.map
to exclude permission issues, but the warning message is the same...

Mapserver version is 4.8.3 on Linux Gentoo

No problems with the same PHP/Mspscript project on Suse 9.2 with
mapserver 4.6.1...

I will be glad if any one of you can help me!!!

TIA

Ruggero