How to not have formula change after inserting column from another sheet

One file - a few sheets. I run a macro weekly to copy column B of my
CURRENT PORTFOLIO sheet and insert that data between Col I and J (Moving
older data to the right - off the screen.) I then populate col B with
this weeks data. That works fine, BUT another sheet of that file (
GRAPH) uses that data to track a few moving averages. To keep the GRAPH
sheet accurate, after the macro I then have to modify the contents for
the SOURCE field of the graph because NOW $I$1 becomes $J$1 and $I$28
becomes $J$28. I can't use an INDIRECT command - I get an error. Name =
Weekly Moving Average, Y-axis = the total of the portfolio, X axis = the
date ( like 1/4/06 ) Here's my current formula:

Source Data =SERIES("Weekly Moving Average",'Current
Portfolio'!$I$1:$BZ$1,'Current Portfolio'!$I$28:$BY$28,1)
How do I prevent $I$ from changing to $J$ after inserting a column on
another sheet ?

Thanks,
Bobb