That makes no sense.

ToChange.qml defines "callUrl" as an alias for "visible" of another element, which is a boolean property.
You can't assign 'T' to a boolean.

If ToClick needs to change the visible property of item1 inside ToChange, then just assign the value you need (true or false) to the alias property.
You might want to use a different name then callUrl, since it is a boolean, not an url

Cheers,
_