Measuring current with multimeter (broken?)
Not to point out the obvious, but reading the manual seems like a good idea:



I know you said you were measuring current correctly, measuring voltage versus current on most multimeters involves moving one of the test leads to a different jack on the meter. Usually current measurements are all done from a jack dedicated to current measurement. However steps 2 through 4 point out that measuring current at different ranges makes use of different ports. In this case, measurements from 0 to 400mA both use the same jack as for voltage measurements (V/mA/&mu;A/CAP/&Omega;/Hz/Temp). I find this a bit unusual, but it could be somewhat convenient for low-current measurements.

As to why the meter shows the same digit (6) at different ranges, most likely because the meter was trying to read current from the jack which wasn't connected to anything during measurements.