Form Field Calendar Date Issue

Hi, I’ve created a form which contains several date fields, which all seemed to work just fine until recently.

I’d entered the following code to ‘reset’ the date so the current calendar pop-up would not select the date used in a previous date field:

if (this.getField("DMSignedDate").value =="")

{this.getField("DMSignedDate ").value = new Date();}

Now I see an error ‘Invalid date/time: please ensure that the date/time exists. Field [Field_name] should match format dd-mmm-yyyy.’

The field does match the format and worked up until the UK clock changed from British Summer time (1 Hour adjustment). Thanks for any help & guidance