Vitamin B6 works with other vitamins, and minerals.
If those are low, the B6 cannot do its job properly.

Your complex should have B2 in it? B2 is the cofactor for
activating B6 in the body to pyridoxal.

Also magnesium is necessary, and if you are low in this,
you may have muscle twitching or cramping as a symptom.

Do not use magnesium oxide--as it is not absorbed well.
Here is my magnesium thread:
http://neurotalk.psychcentral.com/thread1138.html

That thread explains food sources, what magnesium does,
and which supplements are best. There are suggestions for topical use also. Magnesium is a cofactor to process essential fatty acids in your food for use by the cells and nerves.

Some people are very sensitive to B6. Why don't you start
with one of those a day, and increase if you need to over time.
If you stay under 100mg a day, you should be okay. But some
people need to stay under 50mg a day and it is impossible to predict who those sensitive people are.