I've named few ranges through VBA by using this code

For i = 1 To 15

' Define the name for the variables
ActiveWorkbook.Names.Add Name:=Worksheets("ST&GT DATA").Cells(1, i),
RefersToR1C1:= _
"=OFFSET('ST&GT DATA'!R1C1,'ST&GT DATA'!R1C214," & (i - 1) &
",'ST&GT DATA'!R1C216,1)"
Next i

which is working fine, but when i try to refer it in a chart, an error
msg is popping up saying "Your formula contains an invalid external
reference to a worksheet, Verify that the path, workbook, and range
name or cell reference are correct, and try again"

Can any one solve this problem?

Thanks

Gautam VK