Help with banner fill for a newbie

Hi,  I am gradually learning how to use Coreldraw X4 but I have experienced a problem that perhaps someone could help me with.  I have designed some 3d text and would like to place it on a banner.  I have used a banner from the Banner Shapes Tool and have filled it with a preset from the  Fill tool.  The fill I have used is the preset 'Gold Plated'.  However, there is always a corner of the middle section of the banner that is unfilled.  I have tried radial, conical and linear and also filled it without using a preset fill but I always get the same problem. 

Any advice please.  Thank you.  Diana (UK)