IF Formula false condition error based on Dropdown column

Platform discussions
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1

I have the following formula to calculate a total value when a dropdown column is not empty, and to copy the value from another column when the dropdown column is empty.

if({Number of Seats},
{Number of Seats#Labels}*{Cost}*12,
{Cost}
)

{Number of Seats} is a dropdown column;
{Cost} is a number column

The calculation works fine. But the {Cost} is not copied into the column when there is no selection in the dropdown column; instead it results in an exclamation (error) icon, and the message that “one of the parameters is invalid”.

I’ve tried numerous workarounds for this; it should just work. I must be missing something obvious.

Any ideas, greatly appreciated.

2

SOLVED: I swapped the IF function for a SWITCH function and set a default value for {Number of Seats} to zero.