Dimensions - why - same conditions make different results

[uacg0009]

Hi all,

Sorry at first I need to say maybe this problem is a little abstract, because I can't do an example for this.

Problem is :

I have a chart and there are two dimensions in this chart.

situation 1:

the two dimensions are:

1:

2:

And result is :

what I want to say is that you can see there are some data in column Y-1 >= column Y-2, like 2012-03-23>2009-11-07.

BUT if I use these two dimensions, the result is different:

1:

2:

the second one don't change, in the first formula, I want to show the count item cat1 but not period date dt.

The result is :

Now I think you can see the difference, what I want to say is there is no data(period date dt) in column Y-1 > column Y-2.

I don't know why? the data in column Y-1 now all less than 2012-02-10. ( 2012-02-10 is the max period date dt of column Y-2)

why I do this change in the first dimension will affect the nearly all results of column Y-1. All data in column Y-1 > Y-2 are gone.

Is there a method to make the column Y-1  like before and also calculate the count item cat1?

I hope I have clarified what I want and if you have any questions pls tell me.

Thank you so much!