Thundergrip

I'm fairly new to Technic, and I'm having this intensely annoying issue: My buildcraft pumps will pump water from any source, and oil if I place it in the world myself, but naturally occurring pools of oil will simply refuse to pump under any circumstances. I've even taken the same pump configuration that was sitting above oil (and doing nothing), built a box around the pipe, added my own oil, and watched it take it up with no other changes. I'm at a loss here. Is this a bug? Something I'm missing? Help would be really appreciated!