Hi @marting66652718 ,
Make sure you have updated the database structure (Tools > Advanced > Update database structure) disconnect and reconnect.
Make sure the name of input form is same as schema name. Eg, if schema name is abc:test, then input form name also be abc:test (Or cross check entity-schema attribute of the <form> element is same as the schema name. eg, <form entity-schema="abc:test" ... )
And cross check in your schema, the attribute's name is 'label'.
If everything is correct, try clear cache > disconnect and reconnect > preview the input form again