Date Format help

Hi Guys, 

Need some help with the below scenario, 

I have a date column with a format dd-mmm-yy. I needed to change this to dd-mmm-yyyy without adding a new column. Hence i made the date column as measure by using sum. SInce the measure had a total, to hide the total i used another measure. (Display Measure = if(HASONEVALUE(XXPBI_SHIPMENT_MV[Confirm Date]),XXPBI_SHIPMENT_MV[Measure],BLANK())  ). Now to change the format i used another measure with the format function  - format([display measure], "DD-MMM-YYYY). This was not showing all values. Further the year was a sum in some rows. But it was displaying correctly in one page and in another it wasn't. Attached the snippets.