We recommend a new version of TWS: Version 978.1g. Most important feature is to set the API message language to english. This makes it possible to keep the TWS language in your native language, but the API messages which are evaluated by our API client software in english.
When your TWS language is english, no need for this version or for changes in API settings.
If you like to have another TWS language than english, this version is recommended. How to set the API messages to english, is shown in the API settings example in german language. Just mind the orange frame.