Hey there
Usually you shouldn't need a mixer. Do you have it hooked up to an
active DI Box? What mark is it? You checked the battery in the DI Box, right? I know, dumb question...but you would be amazed.
Once the Condenser Mic has Phantom Power it should produce sound like any other mic. Are you going into the XLR input with it? Maybe plug a dynamic mic into the Vox inpunt of the amp just to make sure it works. Then plug your Shure mic into a mixing board and check if that works (with 48V). I usually follow the signal path and check where it stops producing sound.
Hope this helps for now...