Value Error Oemof Investment


during modelling an new Scenario in my actual model Version, a value error occurs. I tried a lot to find out, what is the reason for it. I have implemented an minimal and maximal capacity for the investment-module. I have no idea, why there’s that value error.
Has anybody an idea, what could be the problem?

ValueError: No value for uninitialized NumericValue object InvestmentFlow.invest[PtH2,b_hydro]


Best regards Cj