WiFi connection problem..."connect box is "grayed out".."cancel" box is not.

WiFi connection problem..."connect box is "grayed out".."cancel" box is not. Can't connect to my home WiFi which I know is working fine as I use it with this computer also. My phone screen shows my WiFi system has good signal ...my Wi Fi icon is on the screen and shows "locked". I need to input the password but can't. Any ideas on why the "gray" problem?

Here's the solution to getting my S4 to work with my home router which is a Linksys E1000:
D-Link Connected Home Resource Center » Wi-Fi Protected Setup (WPS): The Easiest Way to Set Up Wireless DevicesD-Link Connected Home Resource Center