How do you set the output of a DMN to the input value?

[mse]

I tried a Business Knowledge Model with a parameter that took the original input (parameter named PT4) and then had it simply return the value with FEEL syntax like the following:

Code: [Select]

PT4
When I call it from the output field of a decision table with the following syntax:

Code: [Select]

BKM1(64)
I get the following error:

Code: [Select]

Warning : DecisionTable "HMI_EngRPM" Output Entry "Rule[1].HMI_EngRPM":BKM1(64) is not simple value for output type "number"
my input type is set to "number" and my output type is also set to "number". Even the BKM "return" value is set to "number".