gradle sync is fine but can't find the class

[pmrzygweb]

after successfully sync the gradle after add implementation 'com.github.iken.tech:IKGroupAvatarView:0.1'
but when I import it in xml, it shows me error

Class referenced in the layout file, iken.tech.ikgroupAvatar.IKGroupAvatarView, was not found in the project or the libraries
Cannot resolve class iken.tech.ikgroupAvatar.IKGroupAvatarView