Macro only partially working

I have a macro that is changing about 10,000 lines of data to a list box using another sheet within the workbook. The issue I am having is when I run the macro, it only changes about 200 lines to use the list box and not the 10,000 lines I asked it to. Currently the file is saved as a .xls and needs to stay that way because most of the people viewing the file do not have office 2010 or later. How can I fix this issue?

Step one should be sharing the code and perhaps a sample of some non-sensitive data... it could be an issue with a count/loop in the macro but without at least that there's no way to know.


Cheers!
Xervice