Power Pivot :: Formula For Row Wise Weighted Average

I have a table in `PowerPivot` which contains the logged data of a traffic control camera mounted on a road. This table is filled the velocity and the number of vehicles that pass this camera during a specific time(e.g. 14:10 - 15:25). Now I want to know that how can I get the average velocity of cars for an specific hour and list them in a separate table with 24 rows(hour 0 - 23) where the second column of each row is the weighted average velocity of that hour?

A sample of my stat_table data is given below:
 
count    vel          hour  
-----    --------   ----  
133    96.00237    15  
117    91.45705    21  
81      81.90521    6  
2        84.29946    21  
4        77.7841      18  
1        140.8766    17  

[Code] ....

In a separate `PowerPivot` table I have 24 rows and 2 columns(column1 is for hours and column 2 for weighted averages) and when I enter my formula, the whole rows get updated with the same number. My formula is:   

=sumX(FILTER(stat_table, stat_table[hour]=[hour]), stat_table[count] * stat_table[vel])/sumX(FILTER(stat_table, stat_table[hour]=[hour]), stat_table[count])