Get start date and end date from a standard chosen period

[#1]

I'm trying to get the startdate of a chosen period (Year and month chosen from two listboxes on a standard master calendar). This is the standard way of representing time in an application.

I am able to get the first year and the first month on doing set analysis, but when i do furter set analysis on that result to get the first date, then I get the errormessage shown in the textbox.

Any suggestions on how I can get the first date of a chosen period like this?

[#2]

Forgot the screenshot:

[anbu1984]

What is your expression?

[#4]

This is the expression (Im only doing it on year for simplicity):

= date (
   min( {1 <  Dato.Year

= {

if ( len(GetFieldSelections(Dato.Year))= 0 ,'2010', right(GetFieldSelections(Dato.Year),4) )

  }  >}

Vare.STARTDATO  )
)

[anbu1984 · Accepted solution]

= date (
   min( {1 <  Dato.Year

= {

$(=Only(if ( len(GetFieldSelections(Dato.Year))= 0 ,'2010', right(GetFieldSelections(Dato.Year),4) )))

  }  >}

Vare.STARTDATO  )
)