I was running smf 1.1.1 and I bought the SMF Gallery pro 1.2 for my site. It installed fine and it worked just as described.
SMF just sent a new upgrade to 1.1.2 and when I was finished upgrading the gallery button was gone. I then un-installed the gallery and tried to reinstall but now I get this error -
This package is already installed, and no upgrade was found!
You should uninstall the old version first to avoid problems, or ask the author to create an upgrade from your old version.
Please remember to always make regular backups of your sources and database before installing mods, especially beta versions.
And the install actions box says this
The package you are trying to download or install is either corrupt or not compatible with this version of SMF.
I am guessing it is the latter?