RANKX - Rank Within Group

Hello.  I am really struggling with RANKX.  What I need to do is rank within each group, I just cannot figure it out.

I have referrals (cases) with multiple detail rows (dimODetail) for medical data.  Each referral can have between 1-15 different rows in the dimODetail table.  Those can be uniquely identified by the Seq column.  What I need to do is rank the rows within each referral based on the Seq.  I need this to be a measure because I may need to rerank if I use a filter (such as only wanting rows where the organs were intended for transplant (OSpecRecoveryFor = "Transplant").

The Seq is NOT unique overall but is IS unique within each referral.  That seems to be part of the problem, but I just don't know why.

This worked in a test PBIX, but it is not working in this PBIX.

MyRank =

VAR CurrentRef = dimODetail[Referral_ID]

VAR AllOrgans =  

        ALL(

        dimODetail[Referral_ID],

        dimODetail[Seq]

        )

VAR OrgansCurrentCase =

    FILTER(

        AllOrgans,

        dimODetail[Referral_ID] = CurrentRef

        )

VAR Seq2 =

    RANKX(

        OrgansCurrentCase,

        dimODetail[Seq],

        dimODetail[Seq],

        ASC,

        Dense

    )

RETURN Seq2

PBIX file is here:  https://mwtn-my.sharepoint.com/:u:/g/personal/dkernen_mwtn_org/ETq8ZS2rnfZBj0oyCFXT6G4BtgbBLmOm3zhh7WLUpOHyEg?e=s05Qpr

Many thanks in advance.

@RANKX