Difference in Difference Method

Hi guys!

For some research we ran a regression analysis in Stata using the Difference in Difference method. this method uses a controlling group of countries to neutralise other effects than the effect of change in regulations. Afterwards we manipulated the data deviding it through year 2011, multiplying it by 100 and then taking the natural logarithm in order to understand the coefficients as ppercentages of change. Doing this we ended up also changing the sign of the value of our coefficients: the normal regression our coefficient was negative and now it became positive. Can someone give some explanation to this?