Couldn't figure it out but perhaps that's why i felt it's off. Mightn't be incorrect per se like someone else points out but not something I'd chose to caption something.

Might be a good idea to revisit and update for better grammar. Staerke sounds like strengthen rather than strong, (verb vs adj) which, if this is the case, sounds wonky. More natural would be Deutschland staerken, or starkes Deutschland. There's a few other bits that sound unnatural also.