User Defined Units Help!

I am new to mathcad and I am just starting to play with simple problems first to learn the necessary interactions with the program to achieve desired goals. I am working on a very simple problem that starts as seen below.

Life_Expectancy:=10yr

CyclesPerYear:=21900cycles

Total_Cycles:=Life_Expectancy*CyclesPerYear=

With this mathcad can not compute the Total Cycles and does not display cycles as a unit. I have highlighted cycles and changed it to units to no avail. I have also tried changing the term cycles to wipes and iteration but neither worked. What am I missing to make this simple problem work? Thank you