Using Concatenate in constraint and age constraint

Hi All,

Am using xlsform and am trying to put 2 integer constraints to work together(separately they work)
-1st constraint to check that the person 2 isnt older than person 1 and
-2nd constraint is to ensure that person 2 is greater or equal to the specified age of 21
For example if
Person 1 is 35 then Person 2 should be below 35 and above 21.
Am using a concatenate =CONCATENATE(".<=${",B35,"}") to validate the person 2 isnt older than person 1 but when adding .>=21 it refuses to save the xlsform.
I have tried the below combinations
=CONCATENATE(".<=${",B35,"}") and .>=21
=(CONCATENATE(".<=${",B35,"}") and .>=21)
=CONCATENATE((".<=${",B35,"}") and .>=21)

What could be the issue?

Regards,

Paul

There is no CONCATENATE command. There is a concat command though. See https://docs.opendatakit.org/form-operators-functions/#combining-strings for more.

Thanks Yaw.
I have switched it to pick the direct name age1 instead of concatenate.