Business process input parameter types. Falsly asking for Strings

I have this Business process which acceps parameters. It has input-parameters of various datatypes.

But when I call this business process as a Sub-process and use the input parameters, it seem's to be expecting only Strings.

Business process parameters: https://i.imgur.com/VgqhwVL.png
Error on Sub-process element: https://i.imgur.com/4LGPb57.png

Errormessage:

Schema has errors: Cannot convert type "Boolean" to "String" 
for the item or parameter "SubProcess1.FilledBySender".