dmx.validate.setErrorMessage not a function

I’m sure I’m missing something but I have a SC form on a web project page (built with Framework 7) that submits to the SC action where there are some validation steps, including checking for a record in the DB. If this validation fails it tries to set the error message on the linked field in the form and causes the following message to appear in the console:

TypeError: dmx.validate.setErrorMessage is not a function. (In ‘dmx.validate.setErrorMessage(r,e.form[i])’, ‘dmx.validate.setErrorMessage’ is undefined)

If it were Bootstrap, I know it works but can’t work out how to use it in F7. Alternatively, I don’t mind the error message not being shown and handling it with a general error notification.