Question --> Warning: Matrix is close to singular or badly scaled.

[Boris Penaloza]

Hi everybody,
I am trying to run an opf simulation using a case.m file with my own data. In 
my case, I have 12 wind generators 750 kW each. However, when I run the opf the 
next warnings appears --> Warning: Matrix is close to singular or badly scaled.!
Does somebody know what it means?
I have also noticed that when I raised the injection power (in the range of 
Megawatts) the simultaion converges. 
What is the issue here??
thanks in advance..
Boris