No Sound From Cartridge Unless Volume WAY UP

Great volume out of one cartridge; no volume (to speak of) out of other; my gear setup:
Turntable: Technics SL-1210M5G
Cartridges: AT150MLX, AT440MLa
Amp: Cambridge Audio 540R
Phono Stage: Cambridge Audio 640P MM/MC

Not sure what the difference is here. Both cartridges are MM and should play fine with the Cambridge 540R/640P combination. Combpliance (re: www.cartridgedb.com) is fine for both. The AT440MLa plays fine and sounds great. I wanted to try the AT150MLX, as most people with the Technics SL=-1210M5G consider this a winning combo. I finally received the 150MLX the other day and spent a lot of time loading the cartridge to get it right and triple checked setup. I used a Mint Tractor to align everything. However, at my normal listening level, I get zero sound; I have to turn the volume all the way up (yes, as far as it will go) to get a decent, slightly loud (not ear-busting by any means) volume generated. I know the cartridge is fine for compliance;…could this be an Output (mv) problem? The 540R does a great job pushing a surround set-up, and volume is fine (like I mentioned) for the other cartridge. Any feedback will be greatly appreciated; I'm really stumped. Thank you very much.