Yum says dependency " libltdl.so.3" is required, but it's already installed?

I'm a Linux noob and have spent a few hours trying to get ImageMagick installed. I finally got an old version uninstalled, but am struggling to get the newest version installed. When I run the following command:

yum --nogpgcheck localinstall ImageMagick-6.9.0-0.i386.rpm

I get the following error:

Error: Package: ImageMagick-6.9.0-0.i386 (/ImageMagick-6.9.0-0.i386)
           Requires: libltdl.so.3

My attempt to get libltdl.so.3 installed

I ran the following command:

repoquery -q -f */libltdl.so*

Which produced:

libtool-ltdl-0:2.2.6-15.5.el6.i686
yaf-0:1.3.2-1.el6.rf.i686
libtool-ltdl-devel-0:2.2.6-15.5.el6.i686

So I tried installing them one by one:

yum install yaf-0:1.3.2-1.el6.rf.i686
yum install libtool-ltdl
yum install libtool-ltdl-devel-0:2.2.6-15.5.el6.i686

But each one failed with:

Package ... installed and latest version

What should I do?

I read to try:

yum clean all
yum update

But that didn't fix the problem. I'm running CENTOS 6.6 i686.