Benno: I would-if other steps don't work do the following:
Go to Histomod's homepage...
http://histomodforum.forumactif.org/There to: "Vos MODS"
...there download this:
http://histomodforum.forumactif.org/t2066-histomod-new-linkYou'll have a doc for the Histomod folders to be activated via JSGME. Find the Histomod Objects folder in that file and click to download it (003_HistoMod_Objects). That will give you all objects and universal files for almost all maps available.
Maps with additional objects and tex usually contain those.
Once you're there you could also try Histo--if you fly UP 2.01 anyway that's the best mod and the most realistic one IMO since jets use a realistic startup procedures and FMs and planes like the P-51 and German fighters also feature seperate FMs and the more complex engine start. You will also have a very (very!) immersive catapult in that for carriers and some other nice features.
Argh...again an advertisment post.
Benno, if in doubt just take the object folder I mentioned, it might really be a great addition for your install.