"Missing Image" icon appears when pasting a graphic

[silvermoonbeam]

I've been working on a large book that contains many images pasted from music notation software. I've done this hundreds of times without problem, including today. But then, apparently for no reason, instead of the pasted image appearing on the page, the "Missing Image" icon shows up. (This is the one with the question mark in a blue box.)

The Mellel Guide says (p. 196):

Mellel stores images in a special folder within the Mellel document . This means that you can, at any point, open the package and remove any of the images from the package.

When this happens Mellel will display a special “Missing Image” icon

But, of course, I've not opened the package to remove an image and, obviously, what I wish to paste wouldn't be in the package yet. I don't know if this matters, but there are 251 auto-titles at present, 278 images, 50 footnotes and a handful of cross references. The Mellel file for the book is just under 26MB.

It has been taking a long time for Mellel to save the document, even when I've made minor changes, but, again, I don't know if that matters. I'm using version 3.1.3b1.

Has anyone experienced this or have an idea of what might be going on?

Thanks!

[silvermoonbeam]

It turns out the problem was with Sibelius 7 and not Mellel. I tried pasting the same graphic into Pages and got a message that the information I was trying paste was corrupt or that I didn't have the proper permissions. That feedback took me back to Sibelius. I had put a page break into the score I was trying to paste and when I removed it I could paste into Mellel again. So, problem created and solved.