Can use SG-View without signal ground wire connection by only using two wires of RJ11

System

How important is it to connect the signal ground wire from the Xantrex GT5.0 DB9 output to my serial connection on my computer? The reason I have to ask is that is what works with the supplies I have available to me, and when I attempted to connect the signal ground, no communication was possible. The Rx light never turned green, and the Tx light was green, and no information was ever received (continuous statement of offline with no additional information sent).

My serial connection was one I soldered together from available parts, which included RJ11 telephone wires and a stereo 3.5mm plug connection to a DB9 female adapter to the computer. What I basically did was connect a DB9 male connector to a RJ11 female plug, made sure my telephone wires were 4 wire and not two wire, then connected that to a cut-off 3.5 mm DB9 adapter. This adapter limits my connection to three wires. Worse yet, it connects to the outer shell protective ground of the female DB9. I then had a wire connection short the 5 pin to the outer shell of the DB9, therefore providing the signal ground connection. I tested everything with an ohm meter. However, this setup didn't work with SG-view/GT-view, but by removing the signal/common ground wire connection, I am able to get at all the data. If I had to do it again, I would take apart the female DB9 at the plug and solder a connection in directly at the pins. Also, if a signal ground isn't required, I wouldn't have to worry about the 4 wire telephone line, could get by with just 2 wire. The nice thing about RJ11 is that you don't have to punch any additional holes since the wire is smaller, it can fit along the seam of the glide rail on the cover.

But reading this post, it appears there could be a potential problem?
http://www.solar-guppy.com/forum/post2734.html#p2734

Or, perhaps there's a problem with shorting the signal ground at pin 5 to the protective ground outer shell of the DB9?
http://en.wikipedia.org/wiki/RS-232

My system info is a net metering grid tied 5.5kW system in Tallahassee, house built in 2007, solar power up since Dec 2009, 4865 kWh generated so far. I have every reason to believe my computer ground and the inverter ground are the same.