Cannot get fields having specific values or characters using like

I need to search a specific value using an api link:

/api/30/trackedEntityInstances/FjpqB0K7zLV.json?program=slz8BujNhMu&fields=attributes[code,displayName]

The fields are showing properly, but I need to get only code values containing LBN inside of them so I tried the following:

/api/30/trackedEntityInstances/FjpqB0K7zLV.json?program=slz8BujNhMu&fields=attributes[code,displayName&filter=code:like$:LBN]

But all data was shown and the filter wasn’t applied. Then I tried the following:

/api/30/trackedEntityInstances/FjpqB0K7zLV.json?program=slz8BujNhMu&fields=attributes[code,displayName]&filter=code:like$:LBN

And still the same. I tried with &like, ilike, like, and still the same.

Any idea?

Links that helped me a little:

[https://docs.dhis2.org/master/en/developer/html/webapi_metadata_field_filter.html](http://API Dev 1)

[https://docs.dhis2.org/master/en/developer/html/webapi_metadata_object_filter.html](http://Dev 2)