Error 1004 - object-defined error when vba code not applicable

Hi AB33,

I finally found a way to isolate enough lines to replicate the issue.

In the attached file, column CI is used as a check (when the macro is pressed, all values should turn to 0 via adjustments made in previous columns). Because some data is missing, you will see that the values don't change the first time you click. Yet if you click a second time, everything changes to values that are highly incorrect.

I can't isolate what seems to create the issue if the macro is run a second time so any help on this would be greatly appreciated.

Also, could you please let me know whether:

. there is a way to automatically adjust the range to the last line of data (which would vary every month) rather than hardcoding it in the vba
. there is a more efficient way to write the code to reduce the processing time over ~70,000 lines.

Thanks again for your help.
S