yes i have been using lowercase for the commands as is shown by the following 
root@smeserver7 ~]# yum clean all
==============================================================
WARNING: Additional commands may be required after running yum
==============================================================
Loading "smeserver" plugin
Loading "protect-packages" plugin
Loading "installonlyn" plugin
Loading "fastestmirror" plugin
Cleaning up Everything
0 headers removed
0 packages removed
12 metadata files removed
0 cache files removed
4 cache files removed
================================================================
No new rpms were installed. No additional commands are required.
================================================================
[root@smeserver7 ~]# yum update
==============================================================
WARNING: Additional commands may be required after running yum
==============================================================
Loading "smeserver" plugin
Loading "protect-packages" plugin
Loading "installonlyn" plugin
Loading "fastestmirror" plugin
Setting up Update Process
Setting up repositories
smeextras                 100% |=========================| 1.9 kB    00:00
updates                   100% |=========================|  951 B    00:00
smeos                     100% |=========================| 1.9 kB    00:00
smeupdates                100% |=========================| 1.9 kB    00:00
Loading mirror speeds from cached hostfile
Reading repository metadata in from local files
primary.xml.gz            100% |=========================|  20 kB    00:00
smeextras : ################################################## 61/61
primary.xml.gz            100% |=========================| 142 kB    00:00
updates   : ################################################## 464/464
primary.xml.gz            100% |=========================| 265 kB    00:00
smeos     : ################################################## 543/543
primary.xml.gz            100% |=========================|  55 kB    00:00
smeupdates: ################################################## 109/109
Excluding Packages from CentOS - updates
Finished
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for php-mysql to pack into transaction set.
php-mysql-4.3.9-3.22.15.i 100% |=========================|  37 kB    00:00
http://ftp.nluug.nl/os/Linux/distr/smeserver/releases/7/smeupdates/i386/RPMS/php-mysql-4.3.9-3.22.15.i386.rpm: [Errno -1] Header is not complete.
Trying other mirror.
php-mysql-4.3.9-3.22.15.i 100% |=========================|  37 kB    00:00
http://mirror.pacific.net.au/linux/smeserver/releases/7/smeupdates/i386/RPMS/php-mysql-4.3.9-3.22.15.i386.rpm: [Errno -1] Header is not complete.
Trying other mirror.
php-mysql-4.3.9-3.22.15.i 100% |=========================|  37 kB    00:00
http://distro.ibiblio.org/pub/linux/distributions/smeserver/releases/7/smeupdates/i386/RPMS/php-mysql-4.3.9-3.22.15.i386.rpm: [Errno -1] Header is not complete.
Trying other mirror.
php-mysql-4.3.9-3.22.15.i 100% |=========================|  37 kB    00:00
http://ftp.surfnet.nl/ftp/pub/os/Linux/distr/smeserver/releases/7/smeupdates/i386/RPMS/php-mysql-4.3.9-3.22.15.i386.rpm: [Errno -1] Header is not complete.
Trying other mirror.
php-mysql-4.3.9-3.22.15.i 100% |=========================|  37 kB    00:00
http://smemirror.fullnet.co.uk/releases/7/smeupdates/i386/RPMS/php-mysql-4.3.9-3.22.15.i386.rpm: [Errno -1] Header is not complete.
Trying other mirror.
php-mysql-4.3.9-3.22.15.i 100% |=========================|  37 kB    00:00
http://sme-mirror.voxteneo.com/releases/7/smeupdates/i386/RPMS/php-mysql-4.3.9-3.22.15.i386.rpm: [Errno -1] Header is not complete.
Trying other mirror.
Error: failure: RPMS/php-mysql-4.3.9-3.22.15.i386.rpm from smeupdates: [Errno 256] No more mirrors to try.
================================================================
No new rpms were installed. No additional commands are required.
================================================================