Error before clean install of os x

I Have iMac 2011 mid.

Today i've added Solid State Drive to my imac. Now I have original 500gb and SSD 240gb on which i planned to do a clean instal of Os X Yosemite. same os x that i had prior to addind ssd. After completing all the physical installation properly, i restarted the sysem to check if the system recognizes my new SSD, before doing a clean installation. Everything worked well. Two hard drives showed up in my disk utility.

Now the problem begins.

By holding option key i get into boot menu to erase both hard drives before installing clean version of os x yosemite.

after erasing the drives im trying to install clean os x, but i get this error "An Error occurred while preparing the installation. Try running this application again."

I Tried changing date and time through terminal (since for some of you it solved the problem), also did a reset PRAM.

nothing works so far!!!!

iMac (21.5-inch Mid 2011)