http://home.mira.net/~kiewavly/PointOne2.html

http://freespace.virgin.net/mark.roper/leak_point_one_tl.htm

Not knowing anything about the equipment from personal experience, your question is a little confusing because it looks like the Point One is an amp, not a pre-amp. The pre-amp is in the control unit (RC/PA/U). I can speculate that:

The input you are using for the TT is correct, but the 3mV sensitivity is too low for your cartridge. I think some modern MC cartridges have fractional mV outputs on the order of a tenth of the input rating of the Leak at 3mV (Ortofon has some 0.2mV cartridges), so it may be just too low for your TT - in that case a matching transformer is in orderas the solution