New message doesn't display the icons (images with link) in my signature

I have a problem with my signature in new messages only - the images with links won’t display, only the plain text. However in responses or forwarded message it is correct. What could be wrong?

One reason this might happen is when you are composing new messages as plain text. 

Go to Menu > Tools > Settings > Mail > Compose > Mail Format, and make sure that HTML is selected.

Thank you! It worked perfectly! Best, Petra