Hello, I am trying to constrain a field called 'sampletime' based on another time field, 'parameter_time1'. Basically I would like the 'sampletime' field to be later than the 'parameter_time1' field, but only if there is a value (a time entry in 'parameter_time1'). If there is no entry, then the constraint shouldn't apply. Here is what I have in the constraint field for 'sampletime':
if(string-length(${parameter_time1}) > 0, '.>${parameter_time1}')
But the constraint of .>${parameter_time1} is applied even when parameter_time1 is blank. Any ideas on what I'm doing wrong?