Bukkit

I probably shouldn't have but I have decompiled a conflicting class of your WarpSigns.jar

Console Printed Error: Line 46
at com.haskehh.warpsigns.listeners.WarpSignListener.clickSign(WarpSignListener.java)

As a result I decompiled the file above and suggest you change the following code.

if(p.hasPermission("warpsigns.create"))
{
if(lines[0].equalsIgnoreCase("[Warp]"))
if(!lines[1].isEmpty())
{
e.setLine(0, (new StringBuilder()).append(ChatColor.GREEN).append("[Warp]").toString());
p.sendMessage((new StringBuilder()).append(ChatColor.GREEN).append("Successfully made a Warp sign.").toString());
} else
{
p.sendMessage((new StringBuilder()).append(ChatColor.RED).append("[WarpSigns] Please state a warp on the second line.").toString());
e.setCancelled(true);
}
} else
{
p.sendMessage((new StringBuilder()).append(ChatColor.RED).append("[WarpSigns] You don't have permission to do that!").toString());
e.setCancelled(true);
}

To my reviewed version (or similar)

Player p = e.getPlayer();
String lines[] = e.getLines();
if(lines[0].equalsIgnoreCase("[Warp]")) check if the player is even creating a warp sign otherwise, do nothing...
{
if(p.hasPermission("warpsigns.create")) check if the player has the permission
if(!lines[1].isEmpty()) etc...
{
e.setLine(0, (new StringBuilder()).append(ChatColor.GREEN).append("[Warp]").toString());
p.sendMessage((new StringBuilder()).append(ChatColor.GREEN).append("Successfully made a Warp sign.").toString());
} else
{
p.sendMessage((new StringBuilder()).append(ChatColor.RED).append("[WarpSigns] Please state a warp on the second line.").toString());
e.setCancelled(true);
}
} else
{
p.sendMessage((new StringBuilder()).append(ChatColor.RED).append("[WarpSigns] You don't have permission to do that!").toString());
e.setCancelled(true);
}

Please review your code and I hope I have helped you here.

For Note: I will be producing a fork of this plugin for my private lan server until you have fixed this bug

For Note: I have also updated my permissions to try to cancel this bug temporaily, but it will cause a server security issue
if this bug remains unfixed. Contact me if you want the build I have fixed. It will not be released without your permission.

MutantSFox