solve block error this variable is undefined

Hi everyone my name is jimmy  from Mexico im student researcher my major is electromechanical  engineer, i have a project for evaluation of PV modules, and one of my  objectives is too use data-sheet information with 4 parameters  Voc,Isc,Vmp,Imp from the PV module to extract another parameters  (a,Iph,Io,Rs,Rp) that not included in the data-sheet. For that im using a  five parameter model to solve that problem, im using the solve block  (Given,Find) for a nonlinear systems, the method im using is the  conjugate gradient. im attaching my file and you will see all the  equations that i use, my problems is that when i put the solve command  an error display appear saying that some variable is undefined and i  check all the file to see what would be the problem and when i use the  track error option put me in the first formula the saying that Iph is  undefined. i will really appreciated if you can help me because im new  on this software

Best regards to the PTC community.