mxtoolbox will not confirm my settings

mxtoolbox will not confirm my settings

Dear Sir,

i have changed my mx settings as in the picture attached but when i look up my mx on mxtoolbox it gives me this error

Lookup failed after 1 name servers timed out or responded non-authoritatively

should i put my source name as blank instead of '@' ? or just wait longer for DNS to propagate even though it says the TTL= 600