Internal error when implementing extension (see long text)

What causes this issue?

An internal error occurred during the implementation of a
customer-specific enhancement. When the API_RE_..._CHANGE or
API_RE_..._GET_DETAIL function module was called, the IO_OBJECT
parameter did not have a type-compatible value.
The called function module belongs to function group &V1&. The IO_OBJECT
parameter however is of type &V2&.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Contact your system administrator.

Procedure for System Administrators

Correct the call of the function module.
The IO_OBJECT parameter should only be used when the call of the
function module takes place in the implementation of a Business Add-In.
Within the implementation of a Business Add-In for an object type, such
as RECN_CONTRACT for the real estate contract, only the corresponding
API function modules of this object type are allowed to be called using
the IO_OBJECT parameter. For the real estate contract object type, these
are the API_RE_CN_CHANGE or API_RE_CN_GET_DETAIL modules, for example.
If you need the data of another real estate object, such as an assigned
rental object, do not call the API_RE_RO_GET_DETAIL module using the
IO_OBJECT parameter. Instead, use one of the various key fields.

Error message extract from SAP system. Copyright SAP SE.