Your theme uses something called timthumb (which I recall was a security issue at some point) and also consumes unneeded resources, I suggest you use a normal image tag and things will probably just work.
Mandhari wako anatumia kitu kinachoitwa timthumb (ambayo mimi kukumbuka ilikuwa suala la usalama katika baadhi ya) na pia hutumia rasilimali unneeded, Mimi mapendekezo ya matumizi ya kawaida na picha tag mambo pengine tu kazi.