Default [Q] Can't instal zip file through CWM

Hey everyone,

I flashed my SGS3 to Cyanogenmod 10.2 (using the cyanogenmod installer so its not rooted) after getting tired of it im trying to get back to stock rom android 4.3 However when i run CWM (version 6.0.4.4) and instal the zip file (downloaded the right version from good source etc.) , CWM says

-- Installing: /sdcard/0/PHN-I9300XXUGMK6-20131228144533.zip
Finding update package...
Opening update package...
Installing update...
Installation aborted.

I have already downloaded the zip file from several sources and all zip files give the same issue. Thanks for any help.