SAP HANA: SQL in Calculated Columns

Hey,

I want to calculate some columns with SQL expressions.

But there is always an Attribute is missing in node finalAggregation error.

Examples:

ceil(days_between("RegisteredOnDate", "RecordedOnDate")/7.0)

Attribute 'days_between' is missing in node finalAggregation

WEEK("RecordedOnDate")

Attribute 'week' is missing in node finalAggregation(CalculationNode (finalAggregation) -> attributes -> calculatedAttribute (RecordedInWeek) -> expression)

I don't understand this error. Column Engine Functions works fine.

Hope you can help me. Thanks in advance.

Kind regards

Fabian