I just tried to install Openmx on my computer. The result is as follows
Installing package(s) into ‘C:\Users\jkarch\Documents/R/win-library/2.12’
(as ‘lib’ is unspecified)
trying URL 'http://openmx.psyc.virginia.edu/packages/bin/windows/contrib/2.12/OpenMx_1.0.6-1581.zip'
Content type 'application/zip' length 2180329 bytes (2.1 Mb)
downloaded 2.1 Mb
package 'OpenMx' successfully unpacked and MD5 sums checked
The downloaded packages are in
Loading required package: OpenMx
Failed with error: ‘package 'OpenMx' is not installed for 'arch=x64'’
On the 32bit version everything works fine.