Modifying the PV model

Hi I am simulating a MPPT algorithm using fuzzy logic. I need to read the current and voltage of the PV model. I tried to modify the model but I could not because it is copyrighted.So I decided to copy the internal structure and build a new model and modify the measurement port, but when I run the simulation this message error arises:

"Invalid setting in 'boostmodified/Subsystem1/Subsystem/Diode Rsh/EgRef' for parameter 'Gain'.

Error evaluating parameter 'Gain' in 'boostmodified/Subsystem1/Subsystem/Diode Rsh/EgRef'

Undefined function or variable 'EgRef'." How to solve this problem?