I was looking on the minecraft wikia - under Lead's, via http://www.minecraftwiki.net/wiki/Lead ; and it reads :

"Bats are the only passive mobs which cannot be attached to a lead, and any mobs which naturally despawn (such as the squid) will still despawn if they are attached, unless the mob was named with a Name Tag."

That being so, I name tagged a bat 'Pedro' - then used a lead on it, but the lead did not work

fix pls