M_map lambert projection

Hello everyone, I'm trying to plot a lambert projection with my temperature data. First of all I plot data with was on a regular grid and everything went well. Then I interpolatet unregular data onto a regular grid I tried to plot it, but somehow it won't plot properly. Here an image for example. As you can see he detects the coastline properly but somehow don't leave them blank where the coast should be.

Maybe someone had a similar problem or has a suggestion why this keeps on happening. Thank you!!

for mon=12
%Nur ein monat temperature
m_proj('lambert','long',[-90 50],'lat',[45 85]);
disp('start plotting temp fesom')
h=figure;
ind=find(vq==0); vq(ind)=nan;
m_pcolor(Lon_oras,Lat_oras,vq(:,:,mon)); shading flat;
caxis([-2 10])
colormap;
cb=colorbar;
xlabel(cb,'Temperature');
m_grid('box','fancy','tickdir','in');
m_coast('patch',[.8 .8 .8],'edgecolor','k');
%title(['year: ',num2str(year),'; depth: ',num2str(depth),' m'],'fontsize',16);
print(h,'lambert_temperaturen_fesom_monat','-dpng');
end