EDIT : Nevermind, problem solved after a CKAN refresh. It seems it didn't install the last version when I reinstalled my mods.
There is some problems on my side. The GroundConstruction-Core is in the list now, but when I install GroundConstruction while the GC-Core is installed, Ckan try to overwrite some files from the GC-Core :
GroundConstruction/GroundConstruction.version
GroundConstruction/KitResources.cfg
GroundConstruction/Icons/applauncher-icon.png
GroundConstruction/Icons/toolbar-icon.png
GroundConstruction/Plugins/GroundConstruction.dll
GroundConstruction/PluginData/GroundConstruction/GroundConstruction.glob
If I delete them manually, the file is still registered to GC-Core, so no install possible.
Or maybe i'm doing something wrong, don't know.
I tried to reinstall all of my mods, no change.