Can't keep peppermint shrimp alive!

[BigRedSpecial]

Are peppermint shrimp known to be fragile? I can't seem to keep them alive. I've added them on two separate occasions; both times they lived long enough to molt twice, but immediately after the second molt disappeared. I thought it was strange because I had a blood and a cleaner shrimp who did very well, but I assumed the blood shrimp was chasing the peppermints enough to kill them.

2 months ago, I lost the blood and cleaner in a pH crash, so two weeks I added two more peppermints; they molted last week then this morning I found one dead. What gives?

pH 7.8
temp 80/26C
SG 1.025
kH 11 dkh
Ca 340
NH3, NO2 NO3 all 0
PO4 0, Cu 0

The only thing I could think of this time would be either starvation(I've never seen one of them eat), or ingestion of joe's juice(I injected sever anemonies on the rock they hung out on)? I'm grabbing at straws here... any ideas?