FFMPEG - Unknown encoder 'libx264'

I'm trying to run the latest SVN release of ffmpeg and libx264 on my CentOS 5.3 server. Both have built and been installed fine, but the following happens when I try to convert a video:

root@web3 [/usr/src]# ffmpeg -y -i 00107.MTS -acodec libfaac -ar 44100 -ab 96k -vcodec libx264 -level 41 -crf 20 -bufsize 20000k -maxrate 25000k -g 250 -r 20 -s 1280x544 -coder 1 -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -rc_eq 'blurCplx^(1-qComp)' -bf 16 -b_strategy 1 -bidir_refine 1 -refs 6 -deblockalpha 0 -deblockbeta 0 output.mp4
FFmpeg version SVN-r20330, Copyright (c) 2000-2009 Fabrice Bellard, et al.
built on Oct 20 2009 12:53:23 with gcc 4.1.2 20080704 (Red Hat 4.1.2-44)
configuration: --enable-libmp3lame --enable-libx264 --enable-gpl --enable-nonfree --enable-postproc --enable-pthreads --enable-shared --enable-libtheora --enable-libxvid --enable-x11grab
libavutil 50. 3. 0 / 50. 3. 0
libavcodec 52.37. 0 / 52.37. 0
libavformat 52.39. 2 / 52.39. 2
libavdevice 52. 2. 0 / 52. 2. 0
libswscale 0. 7. 1 / 0. 7. 1
libpostproc 51. 2. 0 / 51. 2. 0
[mpegts @ 0x8a57420]max_analyze_duration reached
Input #0, mpegts, from '00107.MTS':
Duration: 00:00:10.95, start: 1.000067, bitrate: 4882 kb/s
Program 1
Stream #0.0[0x1011]: Video: h264, yuv420p, 1440x1080 [PAR 4:3 DAR 16:9], 50 tbr, 90k tbn, 50 tbc
Stream #0.1[0x1100]: Audio: ac3, 48000 Hz, 5.1, s16, 448 kb/s
Stream #0.2[0x1200]: Subtitle: pgssub
Unknown encoder 'libx264'


The H264 library is installed in the same folder as the other libs that ffmpeg requires - it hasn't complained about any of those. I have also tried uninstalling ffmpeg and libx264, then installing via YUM instead with stable builds:

root@web3 [/usr/src]# /usr/bin/x264 --version
x264 0.68.x
built on Jul 8 2009, gcc: 4.1.2 20080704 (Red Hat 4.1.2-44)
root@web3 [/usr/src]# /usr/bin/ffmpeg -y -i 00107.MTS -acodec libfaac -ar 44100 -ab 96k -vcodec libx264 -level 41 -crf 20 -bufsize 20000k -maxrate 25000k -g 250 -r 20 -s 1280x544 -coder 1 -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -rc_eq 'blurCplx^(1-qComp)' -bf 16 -b_strategy 1 -bidir_refine 1 -refs 6 -deblockalpha 0 -deblockbeta 0 output.mp4
FFmpeg version 0.5, Copyright (c) 2000-2009 Fabrice Bellard, et al.
configuration: --prefix=/usr --libdir=/usr/lib --shlibdir=/usr/lib --mandir=/usr/share/man --incdir=/usr/include --enable-libamr-nb --enable-libamr-wb --enable-libdirac --enable-libfaac --enable-libfaad --enable-libmp3lame --enable-libtheora --enable-libx264 --enable-gpl --enable-nonfree --enable-postproc --enable-pthreads --enable-shared --enable-swscale --enable-x11grab
libavutil 49.15. 0 / 49.15. 0
libavcodec 52.20. 0 / 52.37. 0
libavformat 52.31. 0 / 52.39. 2
libavdevice 52. 1. 0 / 52. 2. 0
libswscale 0. 7. 1 / 0. 7. 1
libpostproc 51. 2. 0 / 51. 2. 0
built on Jul 24 2009 01:48:17, gcc: 4.1.2 20080704 (Red Hat 4.1.2-44)
Unknown encoder 'libx264'

I can't work out why it's not working. Can anyone help me please?