'On the Fly' Auto Thumbnailer MAX image size

[mh5bl]

I am using this addin and it is great

but I am using some images that are 500 to 600 kb in size 3500 x 3000 pix.

Images of this size, the thumb do not work. (smaller images do work)

see link below:-

http://www.skitalianfurniture.co.uk/catalo...php?cPath=25_27

 

question is there a max images size by KB or pix ???

 

any help thanks