Gnuplot cannot recognize AquaTerm even I have it installed on OSX 10.8.5

Question

I'm trying to install gnuplot on osx 10.8.5 (Mountain Lion), using homebrew.

Here're the steps:

1. download AquaTerm from sourceforge
2. install gnuplot using homebrew: brew install gnuplot

It seems that gnuplot cannot find the installed AquaTerm, because after gnuplot was installed, I have: Terminal type set to 'unknown', although I have terminal type set to aqua.

If I type: set term in gnuplot, it returns me a whole list of terminals, but there's no aqua.

Two possible solutions I've found online and tried, but none of them worked for me:

1. I tried to download the gnuplot source, do local ./configure, I found that the configuration cannot find AquaTerm because of this in the output: aqua: no

2. According to this post, I tried to install XQuartz (replacement of X11), and set term to be x11. I then get the error below:

     Terminal type set to 'x11'
     Options are ' nopersist'
     gnuplot>
     gnuplot: unable to open display ''
     gnuplot: X11 aborted.
   

I think the problem I'm having is that.. gnuplot cannot find AquaTerm, therefore cannot using AquaTerm to display; additionally, it somehow conflicts with the XQuartz term here.

I don't know what to do now.. any help would be appreciated.