Setting a dynamic range for a chart

I have been stuck on this for a while....

I need to create a dynamic range for my chart

It should start at $M$3 and end at $T (the number that comes after "T" needs to be the number found in cell G4)

so if G4=84

the range would be $M$3:$T$84

any help would be awesome

Thanks,
Dan!

Thanks for the quick help...I can't upload the file because of a firewall...

How do i create a named range and what would the format for each of these named ranges be?

Thanks so much,
Dan

(edit)
(if you can not help without the file i compleatly understand)