Cannot upload certain images to site

I am having trouble uploading new PNG files to ToastHost!See image below – it shows a broken icon and just the text name.I was able to upload files that I had uploaded months earlier, and other files but these two, not uploading right.Another adminstrator on the site is having the same issue.If I have reached my maximum space, can you tell me the steps to obtain new server space?Thanks so much!!--Todd Remer Eagles Toastmasters Club  

You haven't provided your club number.  
Please log out of your site as member and as admin if you are admin, and close your browser window.
Then log in (only one access) and try again.

It looks like that worked. Lesson Learned: For uploading images, be sure you only have one access open (the Admin. access).
Thanks!