Hydrogen sulfide peak not showing on SCD GC

I use the DB-Sulfur column in 7890GC in conjuction with a Sulfur Chemiluminescence Detector (SCD) to analyze for sulfur species (H2S, COS, MeSH, EtSH and DMS).

Recently, i am unable to see hydrogen sulfide (H2S) signal; i don't have issues detecting the other sulfur species (their signals / peaks come up)

Setting parameters of the GC and SCD equipment are okay