Dopehead

My KSP upgraded to 1.0.4 via steam, now I have trouble transfering fuel. I have landed a small hopper next to my minmus base fuel factory and I am able to connect it using a pipe. Transfering fuel looks to be working, I can pump it over, but as soon as I disconnect the pipe fuel levels are restored to the way they were before the transfer. Anyone else experience this ? btw, the small hopper was build in 1.0.4. the base is older, probably 1.0.2, dont know if thats relevant.