A RiverWare initialization rule wasn't executing, even though it worked fine as a regular rule. Rule appears to be ineffective.
The rule references an expression slot for a historical diversion schedule.
Expression slots are not calculated until after initialization rules execute, so, in this case, the slot had no data, and the rule was ineffective.
You can correct this problem by creating a normal slot for the rule to use, which you can fill with input values by copying from the expression slot, or assigning values using an initialization rule that performs the same calculation as the expression slot.