why is the calculation wrong?

[#1]

Hello, everyone

I want to calculate the distinct account id for each salesman.If account id doesn't exist, I will calculate the distinct account name instead.But we can see from the result, the if expression is not a right answer.Why?

[#2]

the third expression wouln't be?

if (IsNull([count id]),[count name],[count id])

[#3]

I have tried the solution,but it doesn't work.

[Anonymous]

I noticed that if Id is null also account name is null so maybe you should find another way to count them.

Find an attachment where in yellow column you can see that number of Id null is the same of the account name null.

[#5]

It happens to be that the id is all not null.From the expression result, the right answer should be 91,the same as count id, but the actual answer is the same as count name.Does the "if" function lose effect?