pop_transition_matrix

[Camilla Stefanini]

Hi, I have a doubt on how to build my population_transition matrix: 

the age structure is as shown, seedlings (0), young trees (5) and adults with different stages (30, 50, 70 and 90 years). Almost all the adults are surviving and transitioning to the next stage, once the reach the transition time (every 20 years). 

Therefore, the total P of survival and transition should be 0.98, if I am correct. 

What is not clear to me is: if Psurvival + Ptransition = 0.98, 

how to set Psurvival and Ptransition, given that each class age is 20 years (so the trees stay in the same stage and survive for 20 years with Psurvival = 0.98) and at the transition time they all transition to the next stage (so Ptransition  = 1) ?

Maybe I have missed something basic, sorry and thanks for any input. Below my script to make it clear: 

Thanks, Camilla