make exim with mysql

Hi, we are running the redhat large distribution, we are newbies to linux, we had exim running fine but wanted to set it up with mysql so could have a table for mailboxes etc.

we have changed the correct lines in the makefile (we believe):

LOOKUP_INCLUDE=-I /usr/bin/mysql

LOOKUP_LIBS=-L/usr/lib/mysql -lmysqlclient

SUPPORT_MAILDIR=yes

LOOKUP_MYSQL=yes

AUTHCRAMMD5=yes

AUTH_PLAINTEXT=yes

when we try to make though we get the error:

/usr/bin/ld: cannot find -lmysqlclient

collect2: ld returned 1 exit status

make[1]: *** [exim] Error 1

make[1]: Leaving directory `/root/exim-4.50/build-Linux-i386'

make: *** [go] Error 2

Any help would be greatly appreciated.