As per my understanding below is the code:
Serial Number:
if(ISNULL(rmadtl.ShortChar01))
then
//your code
else
rmadtl.ShortChar01
Date:
if(ISNULL(rmadtl.ShortChar03))
then
//your code
else
rmadtl.ShortChar03
In both the cases checking the null condition and if it is write required code you need else pring the serial number and date
Let me know if this not your requirement.