email subject not translated

Hello,

I use the plugin and the dutch translation. Most of the translation is perfect, but I have one issue. The email subject that the clients revieved after an order is not translate but is in english (Receipt for order #4666 from Hardyprints).
The strang thing is that the email subject that I revieve for notification, the subject is correct translated (Bestelling #4666 geplaatst op Hardyprints).

I have looked to the translation files and it seems to be correct. Also in the email directory of the plugin, I cannot change it.

Does anyone has a tip or hint to solve this issue?

Thanks