[mrtg] mrtg-rrd weird image scaling

[rihad]

Sorry if this is a bit offtopic.
mrtg-rrd draws our links this way: http://link.imgshare.us/24p4xW
Any way I can get rid of the annoying white part? As you can see the
white part is way over the red line (AbsMax).
The thing is that plain MRTG draws the same link load fine:
http://link.imgshare.us/24p4vo
I've tried tweaking some mrtg.cfg values with no success. After looking
at mrtg-rrd.cgi sources it was obvious that it was checking whether
Unscaled was set or not, and turn off rrdtool's image autoscaling based
  on that, but I don't use Unscaled anywhere. Where's the catch?

Thanks in advance for any hints.