If you have VALUES or PARAMETERS based on these in the parameter script, it is possible that the param script is run more than once, and the code you wrote will be executed more than once with different parameter values. Your condition B is based on A, but in the next run A is based on the last run of B.
You might need to use GLOB_MODPAR_NAME in the parameter script, based on which parameter the user changed, only one of the limiting conditions has to be applied.
Péter Baksa
Library Platform, Software Engineer
GRAPHISOFT SE