=Sum Problem

I'm trying to get a spreadsheet document to calculate via =SUM of a total column, to generate this column data it comes from the previous column next to it with the formula "=IF(G2="200",+D2,"")" All this is doing is if the cell G2 is the extension "200" being one of our call centre staff ex.number, it then puts the "call duration" in the cell in and if any other extension in there, it wont include it and they can be a new formula in a different column.

Because the data is imported from our VOIP data source the formulas in the columns work only when the data arrives, so all the blank fields under it are they show as #Value
and =SUM wont work if that's in a field.



What I'm trying to is a total of call time per Ext.number, as I've solved a way to calculate the call amount, i just cant find a way to get the call duration so we can display it on a TV on our wall to motivate staff
Ext 200 = 74 Calls total
Ext 200 = 784 Total Call Duration

Ext 201 = 97 Calls total
Ext 201 = 854 Total Call Duration

Please see attached picture to get a better understanding of my problem, I'm sure there are very clever ways to solve it but this is the only way i can work out a way to get it to work.

Here is the file, its 37mb so it wont upload.
http://wikisend.com/download/440042/Call Report.xlsm