my papyrus' new growth keeps dying -- any ideas?

[vitaminz]

I purchased the Papyrus plants (2) about 2 months ago. I later noticed that old growth was sagging and new growth was dying. The set-up is fine. The soil is granular (it's not sitting in standing water) and kept very wet. Right after purchase I noticed black spots on the stalks. I took samples to a local nursery -- they said it was black mold and gave me a fungicide to help take care of it. The latest new growth starts out looking fairly nice but turns black in the center where the new grasses are coming out. They start dying from the center out. I can't figure out what to do. Suggestions??

Thank You,

vz