I have had an off grid system running 1 x 90watt panel, has been running great for the past 2 months or so.

Have finally gotten the budget to add a 2nd panel, I have added it in series - so keeping the 12 volts, but doubling the amperage...

However for some reason its not increasing and I cant figure out why.

I have tried googling, as i thought for some reason it may not work...and I came across things like this:

http://cleangreenenergyzone.com/solar-power-panels-or-cells-in-parallel-circuits/
http://au.answers.yahoo.com/question/index?qid=20100120064759AA8YgR8

now that says exactly what I was expecting. 90 + 90 = 160.
I have tested them singularly, and they are both putting out 4.5 amps. (which being sunny today, is about right)
but when they are both connected, they still only put out 4.5amp.

I have double checked the fuses, I have checked to make sure I got positive and Negative around the correct way,
With both connected 4.5amp
with panel one connected 4.5amps
with panel two connected 4.5amps

why doesnt the amperage increase after they join?

When I setup the system, it was done for there to be 5 panels eventually,

How they are wired:
Panel ---> Positive ---> 6way fuse box with 10amp fuse ---> distribution bar ---> 1 fat cable to solar controller positive
panel --> Negative --> distrution bar ---> 1 fat cable to solar controller negative

I dont think the fuse box is needed, but I added it anyway to make sure the panels didn't try to fry each other.