Editing problem - Rome total war.

[Describe]

Im trying to edit my unit, making my own following a tutorial.
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However when i go to save the coded text, it comes up the following message:

Access: to C:\program files\The creative assemblyRome-Total war\data\export_descr_unit_enums.txt was denied.
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How is it denied!?
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I cant seem to edit any Rome Total War Files, Help is appreciated!

And rep is given to suitable respones and facts/help. - Thanks, Joey.

[Agent 47]

Are you running Rome total war when trying to edit? If so, quit it and try again, when a program is using files, access is usually denied.

[Describe]

Nope - I wasnt using it when trying to edit, id closed every programme except from thye tutorial and it still didnt work - Thanks for your help anyway and +rep.