Can't figure why Master Jewelry Writ not "taking"

[iccohen]

I have enclosed a screenshot showing that I need to create Vastarie's Ring. I'm in the proper location (Northern Elsweyr), have the proper material (platinum), proper trait (health), and proper level (Epic).

Yet it does not recognize this. Do I need to do the whole set?

I am at 50/CP160, level 50 in Jewelry. I am 1/3 in Platings Expertise - could this be the issue?

Thanks in advance for your help!