Mario, I've read the url above but I think it's not the problem because I'm using an old version of CUPS (cups 1.1.22.rc1.9.11) for enterprise restrictions.
Anyway reading the error log I see the job seems to be sent but the printer never receives it:
I [10/May/2007:13:37:29 +0200] Started backend /usr/lib/cups/backend/ipp (PID 53 30) for job 2.
d [10/May/2007:13:37:29 +0200] StartJob: Adding fd 8 to InputSet...
d [10/May/2007:13:37:29 +0200] add_job_state_reasons(0xb7ccf008[6], 2)
D [10/May/2007:13:37:29 +0200] ProcessIPPRequest: 6 status_code=0
d [10/May/2007:13:37:29 +0200] ProcessIPPRequest: Adding fd 6 to OutputSet...
d [10/May/2007:13:37:29 +0200] WriteClient: Removing fd 6 from OutputSet...
I [10/May/2007:13:37:29 +0200] [Job 2] Connecting to sauron on port 631...
d [10/May/2007:13:37:29 +0200] ReadClient: 6, used=0, file=-1
d [10/May/2007:13:37:29 +0200] ReadClient: httpGets returned EOF...
D [10/May/2007:13:37:29 +0200] CloseClient: 6
d [10/May/2007:13:37:29 +0200] CloseClient: Removing fd 6 from InputSet and Outp utSet...
I [10/May/2007:13:37:29 +0200] [Job 2] Connected to sauron...
D [10/May/2007:13:37:29 +0200] [Job 2] Getting supported attributes...
D [10/May/2007:13:37:29 +0200] [Job 2] document-format-supported (27 values)
D [10/May/2007:13:37:29 +0200] [Job 2] [0] = "application/octet-stream"
D [10/May/2007:13:37:29 +0200] [Job 2] [1] = "application/pdf"
D [10/May/2007:13:37:29 +0200] [Job 2] [2] = "application/postscript"
D [10/May/2007:13:37:29 +0200] [Job 2] [3] = "application/vnd.cups-postscript"
D [10/May/2007:13:37:29 +0200] [Job 2] [4] = "application/vnd.cups-raw"
D [10/May/2007:13:37:29 +0200] [Job 2] [5] = "application/vnd.hp-hpgl"
D [10/May/2007:13:37:29 +0200] [Job 2] [6] = "application/x-cshell"
D [10/May/2007:13:37:29 +0200] [Job 2] [7] = "application/x-csource"
D [10/May/2007:13:37:29 +0200] [Job 2] [8] = "application/x-perl"
D [10/May/2007:13:37:29 +0200] [Job 2] [9] = "application/x-shell"
D [10/May/2007:13:37:29 +0200] [Job 2] [10] = "image/gif"
D [10/May/2007:13:37:29 +0200] [Job 2] [11] = "image/jpeg"
D [10/May/2007:13:37:29 +0200] [Job 2] [12] = "image/png"
D [10/May/2007:13:37:29 +0200] [Job 2] [13] = "image/tiff"
D [10/May/2007:13:37:29 +0200] [Job 2] [14] = "image/x-bitmap"
D [10/May/2007:13:37:29 +0200] [Job 2] [15] = "image/x-photocd"
D [10/May/2007:13:37:29 +0200] [Job 2] [16] = "image/x-portable-anymap"
D [10/May/2007:13:37:29 +0200] [Job 2] [17] = "image/x-portable-bitmap"
D [10/May/2007:13:37:29 +0200] [Job 2] [18] = "image/x-portable-graymap"
D [10/May/2007:13:37:29 +0200] [Job 2] [19] = "image/x-portable-pixmap"
D [10/May/2007:13:37:29 +0200] [Job 2] [20] = "image/x-sgi-rgb"
D [10/May/2007:13:37:29 +0200] [Job 2] [21] = "image/x-sun-raster"
D [10/May/2007:13:37:29 +0200] [Job 2] [22] = "image/x-xbitmap"
D [10/May/2007:13:37:29 +0200] [Job 2] [23] = "image/x-xpixmap"
D [10/May/2007:13:37:29 +0200] [Job 2] [24] = "text/html"
D [10/May/2007:13:37:29 +0200] [Job 2] [25] = "text/plain"
D [10/May/2007:13:37:29 +0200] [Job 2] [26] = ""
D [10/May/2007:13:37:29 +0200] [Job 2] printer-uri = "ipp://sauron:631/printers/ lj2430"
D [10/May/2007:13:37:29 +0200] [Job 2] requesting-user-name = "oliver"
D [10/May/2007:13:37:29 +0200] [Job 2] job-name = "Java Printing"
I [10/May/2007:13:37:29 +0200] [Job 2] Print file accepted - job ID 14647.
I [10/May/2007:13:37:29 +0200] [Job 2] Waiting for job to complete...
d [10/May/2007:13:37:29 +0200] UpdateCUPSBrowse: (126 bytes from 192.168.0.222) 9016 4 ipp://sauron:631/printers/lj2430 "" "lj2430" "HP LaserJet 2430 Foomatic/h pijs" job-sheets=none,none lease-duration=300
d [10/May/2007:13:37:30 +0200] select_timeout: 11 seconds to process active jobs
d [10/May/2007:13:37:30 +0200] UpdateCUPSBrowse: (126 bytes from 192.168.0.222) 9016 3 ipp://sauron:631/printers/lj2430 "" "lj2430" "HP LaserJet 2430 Foomatic/h pijs" job-sheets=none,none lease-duration=300
d [10/May/2007:13:37:31 +0200] select_timeout: 11 seconds to process active jobs
d [10/May/2007:13:37:32 +0200] UpdateCUPSBrowse: (122 bytes from 192.168.0.80) 2 0006 3 ipp://as1:631/printers/lj2430 "" "Impressora en brut" "Local Raw Printer" job-sheets=none,none lease-duration=300
d [10/May/2007:13:37:33 +0200] select_timeout: 11 seconds to process active jobs
d [10/May/2007:13:37:39 +0200] PID 5330 exited with no errors.
D [10/May/2007:13:37:39 +0200] UpdateJob: job 2, file 0 is complete.
d [10/May/2007:13:37:39 +0200] UpdateJob: Removing fd 8 from InputSet...
D [10/May/2007:13:37:39 +0200] CancelJob: id = 2
D [10/May/2007:13:37:39 +0200] StopJob: id = 2, force = 0
D [10/May/2007:13:37:39 +0200] StopJob: printer state is 3
d [10/May/2007:13:37:39 +0200] StopJob: Freeing status buffer...
d [10/May/2007:13:37:39 +0200] SaveJob: Closing file 8...
d [10/May/2007:13:37:39 +0200] SaveJob: Closing file 8...
As i see this topic is too off-topic I'll move it to the cups forum (I didn't knew it exists).
Thanks to all for your support, it's good to see people helps each other!