Problem closing calendar with userform

Hi,

I have a userform where I introduce the dates with a small calendar that pops up. The problem is that each time I close the calendar (pressing the cross key incorporated in that calendar) displays in the textbox a default date instead of just leaving the textbox contents as it was...

I have attached the file so that you can see better whats going. I have put a background color of red on the cells in which occurs that.

Thanks!!