can't catch name tags by fishing!

While fishing - sometimes it catches something but gives nothing. I am fishing since the last week(1 hour each day) and i noticed that sometimes it catches something but it gives nothing and in those 7 days i never got any name tags(i do use max enchanted fishing rod) i am pretty sure that its a name tag that is bugged or something. and it happens a lots of time or maybe when it is a name tag.😐