contentBlockerWithIdentifier blockedResourcesWithURLs does not trigger

• (void)contentBlockerWithIdentifier:(NSString *)contentBlockerIdentifier blockedResourcesWithURLs:(NSArray<NSURL *> *)urls onPage:(SFSafariPage *)page

does not trigger I have put this into the info.plist of the Safari Extension:

<key>SFSafariAssociatedContentBlockers</key>
<array>
	<string>com.thomas.bodlien.software.JavaScript-Blocker.ContentBlockerExtension</string>

What could be the problem?