Invalid Prompt Definition (IES 00005)

Hi all.

I have a derived table with prompts in the where clause and is not validating due to the error Invalid prompt definition.  I was able to get that the issue is with one prompt

@Prompt('Pre-set Day Filter:', 'C', 'Time\Day Date Range', Mono, Constrained, Persistent, { 'Today' }, USER :1)

I have the object Day Date Range already defined and validates just fine.  Is there something someone can shed some light on?

Thanks in advance!

Eileen