Whenever I wanted to fill a PivotView's datasource with data whose Value property could be null, the grid would not display them correctly, but instead would change every cell's value to '1's.
I found what caused my problem:
I just changed that row to:
vMat[len][tkln] = data[len][key];
After that it worked perfectly for me, since I cant really think of a situation where I would want the cells of the grid to all become '1's, rather I want them to keep their value even if they are null.
I guess the feature I would want is to be able to specify somewhere to NOT change the cells values to '1's.