help with m_map bathymetry projections

Hi!

Can someone please advise me how to resolve the following....

h1=figure; m_proj('stereographic','lat',-90, 'long',0,'radius',60); m_elev('contourf',[0:-500:-6000],'LineStyle','none')

produces a projection with a nasty white line eminating from -90lat but the raw data (which I have extracted) has no missing data!

Confused!?! Thanks!