Can anyone tell me the proper way to submit preview image for watermark at delivery?

[mahfuzazam]

I’ve been setting up a single image with the work file to get the preview image for my gig! But it’s not showing for the last 2 delivery. Should I report it to CS?
Is there any rules for submission of the image?
Please help.

[meddlinx]

Make sure you use the fiverr supported file type extensions.

[mahfuzazam]

Make sure you use the fiverr supported file type extensions.

I’ve used it. It worked before. But unfortunately for the last 2 clients, it’s not showing!