Welcome to the OpenSolver on-line help.
I hope that most of your questions will be answered on the Using OpenSolver page. However, if you still have a question, please post it below.
Excel can have problems dealing with add-ons. Visit http://www.add-ins.com/how_to_repair_office.htm for a guide on fixing these.
Here are some fixes for common problems.
1/ Unable to find the external solver ‘cbc.exe’ …
If OpenSolver reports this problem, then it could not find the “cbc.exe” file that comes with OpenSolver. (This file may just appear as “cbc”.) Please check that you have extracted (i.e. un-zipped or uncompressed) all the files from the OpenSolver download.
2/ The CBC solver did not create a solution file.
If this error is reported, then it is likely that OpenSolver was unable to run the “cbc.exe” file. (This file may just be named as “cbc” on some systems.) This may happen if the OpenSolver files (including cbc.exe) are in an ‘untrusted’ location, and so Windows will not let cbc.exe be run. To identify this problem, please find the “cbc.exe” file in the same folder as OpenSolver.xlam (which may appear as just OpenSolver on some systems), and double click on this ‘cbc.exe’ file. You should then see a command window open that starts with the text “Welcome to the CBC MILP Solver”, and gives version information etc. If you don’t see this, then Windows should give you an error message to help you diagnose the problem. It may help to move the OpenSolver folder (and all the files it contains, including OpenSolver and cbc) into a location such as your Documents, or even into Program Files, and try again.