My first trial to produce an APK finaly produced a "corrupted file" error

I Realized that the minimum Android version shows up to 5.1
(My Android device is running 7.1.1)
So far...so logical, the apk might not be corrupted.. most likely set with the wrong min¦ version
PROBLEM: What I cant figure out is why is my list of available Android Versions ending at 5.1...
while My Android SDK shows installed versions of 4.0, 7.0 plus 7.1 installed ¿
Would this come from a Mess instalation or some Version Comunity Plus 9.0 limits ?
...or what else can "hide" to the LC pref. those 7.xx versions ?

thanks for your ligths !
