Chart updating problem

I have a spreadsheet for option modeling. Auto recalc of the spreadsheet is disabled. It has 2 macros that we are concerned with.

Macro A
gets data from a remote source, and then waits for the data download to complete. This updates a bunch of cells on the spreadsheet. This data is NOT charted. After data download is completed, (after receiving a callback from the remote source) it calls Macro B. This updates more cells in the worksheet, which is the source data for the chart. This fails to update the chart based on new values. Even hitting F9 doesn't help

Macro B
However, if I run this macro directly (from a hotkey), it updates the chart with new values.

Any idea why this is so and what needs to be done done to fix the problem? Manually running Macro B is inconvenient. Thanks!

Edit: Using Excel 2007 in xp 32 bit

Could you paste the line(s) where Macro B is called and few lines around it.

Of course an entire example file would be the best