Contracts - How to Restrict Behind Tech Tree Nodes?

[OKTO Enjoyer]

I'm working on an unmanned start tech tree mod, and one of the changes I'd like to add outside the tree itself is gating some types of contracts (Kerbonaut Rescue and Space Tourism) behind tech tree nodes, as trying to complete them before the appropriate tech becomes available would either be very difficult or outright impossible. Looking at the Contracts.cfg file, there were some vanilla contract types that seemed to work like this, and they both included the line

TechNodeRequired = <tech tree node id> // The Tech tree node that must be unlocked to be offered this contract

However, adding the line 

TechNodeRequired = generalConstruction // The Tech tree node that must be unlocked to be offered this contract

in Tour // Tourism Contracts hasn't seemed to work, as I'm still seeing space tourism contracts as soon as I launch my first rocket out of the atmosphere and upgrade my mission control.

What am I missing?