Please help! multiple drop downs dependent on first

hi guys,

new to these boards.

i have a second drop down which is dependent on the first drop down but for the life of me, can't figure out how to get a third drop down to be dependent also on the first. in the attached screen shot, folks will select on the main sheet a "dept" which is referenced to column K.

after selecting "CRS" (as an example), the next drop they can select is from column O "CRS LIST". I have this part WORKING.

This is the part I need help on.

The third drop down they can select from should reference column R "CRS-JOBS" but I cant get it to show up. Can someone please help? I am desperate!

Thank you

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