Does not work on multisite

Hi,

this is a cool plugin, but I have an issue with multisite – the main blog site works fine, but the sub sites report the following error when trying to generate watermark on images:

Error: Attachment do not have sizes or watermark do not setuped

Like I said, this only happens on subsites, which leads me to belive this might be an issue with the location of the watermark in relation to the multisite url structure, anyone else have a clue what might be the problem? I tried this filter ‘berocket_watermark_apply’ but no luck, I thought that by setting a static image for the watermark would fix the issue, but maybe I misunderstood the filter.