I am feeding square wave (0-5V) at 1kHz through a [AD713JNZ](http://www.farnell.com/datasheets/2253286.pdf) op amp which I have wired up as a unity gain buffer, but I'm getting 5V DC on the output:

[![enter image description here](https://i.stack.imgur.com/QAIzH.png)](https://i.stack.imgur.com/QAIzH.png)

What am I doing wrong?