Based on this above screenshot - it looks like that Reference Interest Rates for this yield curve - have been maintained for date 20.08.2015.
But it is not able to find any value for 21.08.2015.
So can you please maintain the reference interest rate for this date.
If you say that you will not receive the interest rate daily then you need to check how your yield curve is configured.
Calculation method of Yield curve --> Check for :
1. Read Procedure
2. Interpolation Procedure
3. Interpolation basis.