I'm just curious why my answer was removed. I asked the poster some questions about his problem then provided two principles to solve his situation.
A(deleted):Do you have something in series with the wire to limit the current? A 2m wire connected directly to 12V should pull a lot more current than 20 mA. What kind of 12V battery is this? Is the battery voltage staying at 12V when you connect it? Batteries tend not to survive long with wires connected directly across their terminals, perhaps it is dead or dieing.
Two ways to increase the magnetic field: more current and/or more wire.
Anyway my second concern is that this is just one example where someone is obviously trying to experiment and learn something without help. Yet rather than just let the question stand they see some back and forth about the site policy and the question gets closed. I've seen this on other questions too. It bothers me because I would rather encourage people to try rather than just close their questions.