>>>>Try using decimal 0 constant. Google on how to set it up correctly, I don't think it's 0.00 as it would be in SQL Server.
>>>
>>>0M
>>>but it is irrelevant here.
>>
>>I was just answering direct question as how to fix the conversion issue (I had similar problems before). But in the whole code we don't really need a conversion, as the sum will result in 0 anyway.
>
>I don't understand but OK.

In his code he doesn't need ?? operator, I believe.