gathering stone

[nmoral]

in every resource if i hover mouse over them i can see the income and how many peasants are working on it except stone...i got 2 peasant groups gathering stone but under resource quantity number is displayed +0 as gaining, and no peasants counted as working on it....and it seems it is not raising or if it does it is so slow i cant notice...

Am i doing something wrong? i can see the little peasants animation gathering stone and carrying it to the char i placed right next to them...