Question : Print nvarchar doe not print any output

I have a stored procedure which I want to debug
I have a few fields that are nvarchar(4000)

example @SqlString   nvarchar (4000)

This field is set to some text, when I do a print there is no output
PRINT @SqlString  

so when I do the follow exec sp_abc , i expected the print to output some information
If i add PRINT 'TEST' , i do see this being output

Answer : Print nvarchar doe not print any output

If you are building up @sqlstring progressively, any time you add a NULL to it, the entire string becomes null and print null = no output.