Leave no Doubt in UX

I found this example in a webform.

OK at least there’s an example so they do get points for that.

But this example does leave room for doubt wich is easily removed by some minor alterations.

Make it. ‘vb.: 23/01/1980’ and there’s no mistake what so ever what’s the days and what’s the month.

When designing something always ask yourself (or others): “is this clear without any doubt? If not how can i Fix it.”

 

 

The same form prompted me with the following after completing it and hitting send.

 

It tells me my ‘social security number’ is already in use. Implying I have an account. Well why don’t you tell me what to do next?

I need a username or email address when singing in. I’m confident I have to guess for both and there’s a 70% chance I will not find out what I used years before. So what other steps can I take?

This error message just leaves me with a ‘it can’t be done’. No alternatives or solutions.