Last week, I did my first wheel build. Mavic open sport rims, Campagnolo Daytona hubs, 36 Dt Swiss competition spokes (DB) and DT swiss brass nipples. 3X.
Based on the writings of Sheldon Brown, John Allen and Martin Gerritsen (framebuilder who has an excellent website in Dutch) I prepped the spokes with linseed oil, I laced everything up, tensioned everything nice and even until all spokes had the same pitch and then trued the wheels in the frame. I then took the wheels out, stretched the spokes, crunched them in pairs and treated the spoke heads with a punch to settle them in the hubs. Then final tensioning and truing.

So far, so good. However, after about a 100 km's (two training rides and one 30 km commute in a veritable monsoon) I pulled the wheels out of the frame, because I had some brake rub. I expected nothing serious, but boy, the wheels were a mess! Tension all over the place, and some spokes were just slack, with two or three windings of the thread showing!

What went wrong? Tension not high enough? Should I've left the linseed oil to dry some more? Do I need loctite?

Anyway, I tensioned and trued them once again, and now they seemed to hold up fine, but two rides isn't exactly long enough to tell wether I got it right.

Please share your wheelbuilding tips!