Ubuntu can't find lilypond executable

[Bertalan Fodor (LilyPondTool)]

I tried to install LilyPond 2.12 on an Ubuntu machine. I found a very strange thing I couldn't explain, and couldn't solve.
I used the script to install:

sudo sh lilypond-X.Y.Z.linux-x86.sh

Then I try to run lilypond:
lilypond test.ly

and I get:

exec: 4: /usr/local//lilypond/usr/bin/lilypond: not found

But the file is actually there:

stat /usr/local//lilypond/usr/bin/lilypond

File: `/usr/local//lilypond/usr/bin/lilypond'
Size: 3586224         Blocks: 7016       IO Block: 4096   regular file
Device: fd01h/64769d    Inode: 755771      Links: 1
Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2009-01-19 10:24:01.000000000 +0100
Modify: 2008-12-31 19:13:22.000000000 +0100
Change: 2009-01-19 10:23:10.000000000 +0100

Could you please help me on this?

Thanks,

Bert