Prevent Dates from being changed

Can you add an expression to the enabled section of the control when ID is not null AND {Self} is not null? Can't test at this moment as not at machine but let me know how you go?

As suggested by Cassy Freeman , add the following condition

not(isNullOrEmpty({Self})) && not(isNullOrEmpty({ItemProperty:ID}))

but instead of adding it as an expression to the enabled section of the control add it to a new rule because the former does not have the name control tab (using which you will add the {Self} property)

Ah good shout!! Without sitting at my machine I was just trying to imagine what it would look like!! 

Still you did a pretty good job with the logic !!

Thank you all for the help, it works perfectly ! 

Glad to hear that !

Could you please update the thread as solved.