Calculated field using smart variables

[Mbusiseni Ngema]

Good Day All,

Kindly assist me I need to create a calculated field from the repeating instrument where I check for Culture results from previous instance compared to Culture results from current instance, where if culture results from previous instance is positive and culture results in current instance is negative  the calculation must return 1 as 'YES' or leave it blank. I am trying the formula below

 

if([culture_result][previous-instance] = '1' and [culture_result][current-instance] = '2',1,"")

However the above formula returns a syntax error message in my RedCap instrument. Anyone's help will be highly appreciated.

Kind Regards,

Mbusi