Everyone has been having this problems and all are aware of this that, Yast2 fails to install from the local directory. Make a note of the weblink from where you downloaded the rpm package. All you need to do is goto "Installation sources" under Yast2 control panel and click on "Add" button. Select Add URL and type in or paste the weblink (website link without the package name, I mean the complete path to the directory containing the packages) and click on Finish.
Once done, launch Yast2 package installer which should list all the packages on the website you just specified. Select the packages you want installed and Finish.
Check these links out:
You can try rpm command also.
BTW, why do you need xorg-x11-devel package ?