startkde - Error creating tmp directory on 1st kde4 login.

[lexual]

Here's the error I get when trying to run kde4 for 1st time :

Link points to "/tmp/MYUSERNAME-kde4/kde-MYUSERNAME"
Creating link /home/MYUSERNAME/.kde4/cache-MYHOST.MYDOMAIN.
Error: cannot create directory 
"/var/tmp/MYUSERNAME-kde4/kdecache-MYUSERNAME": No such file or directory
startkde: Call to lnusertemp failed (temporary directories full?). Check 
your installation.

I need to manually run this command to be able to login.:

mkdir /var/tmp/MYUSERNAME-kde4