Pom paper training problem

We purchased our female Pomeranian at age 10 weeks. We immediately
began paper training her. She wasn't very cooperative at first but
then after about a month it seemed she was catching on. When ever
possible we would catch her and bring her outside to go.

At about age 3 months I started bringing her home to my house due
changes in our work hours. She now stayed at my house mornings and at
my girlfriends house after she got out of work mid afternoon. So now
I was paper training her at my house as well. Again she seemed to adjust
quickly to the idea. Then at some point at about 5 months age she
began avoiding the paper at my house and picking random places
to soil/wet. At the same time at my girlfriends, she would put the dog
out to do her thing more and more, but then the dog stopped going
and would wait until she got back into the house to soil/wet.

Our poor pooch appears to be quite confussed now as to where she
should be doing her business. Since she spends most of her
time at my girlfriends she'll use the paper there at least. But
at my house she tends to avoid it altogether. Sandy ( the Pom )
is now going on 7 months old.

I work part time and am only gone 4-6 or so hours a day. My girlfriend
puts in anywhere from 8 to 12, and that is why we began sending the
dog to my house in the morning, that the dog would be left alone as
little as possible each day.

Besides splitting Sandy's residence between both our houses, what
else are we doing wrong and what should we do to correct our
problem ? Any help would be appreciated.

Paul