According to OData protocol, the value within the parenthesis following the entity set(corresponds to a controller) must be a key, for example:
- ~/odata/Products(1) if the key is of int type,
- ~/odata/Products('1') if the key is of string type.
So please make sure the key is of string type in your case, and try to
GET https://127.0.0.1/odata/ControllerName('param')
to see whether the response is as expected.