Text Frame on Graphic Issue

I have a text frame on top of a graphic for a Cover page as above.
As soon as I try and enter text in the frame, the line background goes white, as below.

The only way round it is to click on the graphic and select Send to Back.

However, it doesn't seem to remember the setting. If I enter text in the text frame again, the same thing happens. I've tried everything to try to get this to stop but I can't fathom it out. Anyone any ideas? I'm on FM 11 if that makes any difference?
Cheers
Mark
