plugins problem

hi
Am still having problems with plugins.
First layerslider asking me for a purchase code but i dont have one…
second isotope gallery every time i download it i can extract the files,message..[a problem is preventing this folder from being encrypted.] went i finally manage to extract and up load to my serve he does not work and i get this message..[Warning: require_once(/homepages/42/d554387461/htdocs/clickandbuilds/WordPress/MyCMS2/wp-content/plugins/sk_isotope_gallery//com/riaextended/php/plugin_core.php): failed to open stream: No such file or directory in /homepages/42/d554387461/htdocs/clickandbuilds/WordPress/MyCMS2/wp-content/plugins/sk_isotope_gallery] i check inside the folder in my server and i think folder [com] and [css] are missing, maybe this is the number one problem but am not sure..
thanks