Hello,
You're probably using the latest version of didnapper (1.2.0) and, as mentionned in the mod's page, it's not compatible with 1.2.0 yet.
Viewing post in Didnapper 2 - Yuti's mod comments
Yeah, I'm just waiting a bit, because bugs are fixed everyday on the main game, as the truh update has just been released on sunday. So I may start working on the compatibility update in few days. But there are lot of things to do and adapt, as the Truth update changed a lot of things. So it may take a while.