Getting error while message search

Im using UI kit 2.7.1
there im trying to use message search in group channels
i followed doc
and i’ve turned on message search feature in dashboard
when i try to hit this
https://SENDBIRD_API_TOKEN.sendbird.com/v3/search/messages?custom_type=custom_type&query=KEYWORDlimit=99&reverse=false&exact_match=false&channel_url=CHANNEL_URL&sort_field=score&advanced_query=false
im getting response as below

{"error":true,"message":"\"GET Search Message\" failed.","code":500901}

if I remove channel_url and custom type im getting response as
{"next":"","start_cursor":"","end_cursor":"","has_next":false,"has_prev":false,"total_count":0,"results":[]}
Although i have the search keyword in channels.

can any one please help here?