Hi @Lilith , that is almost certainly due to a mis-match with the variable names. You should usually run the simulation once, take a look at the resulting ‘.rdd’ file, and then use the names from there directly (copy / paste, don’t try and re-type - the spelling matters). For reference, take a look here:
Take a look here:
Note, if the name you want isn’t in the RDD, you need to add it as an output variable before running the simulation.