Sergv
It does seem to work for me if I do the following

Assume data is in a range A1:C2 on Sheet1 in file Book1.xls
Jan | Feb | March
123 | 234 | 345
Define the following names
myGraph=OFFSET(Sheet1!$A$1, 1,0, 1, COUNTA(Sheet1!$2:$2))
myTitle=OFFSET(mygraph,-1,0)

Then set up your graph
Series1=SERIES(,'Book1.xls'!myTitle,'Book1.xls'!my Graph,1)

Post back if you still have problems

hth RES