Pass NULL String in the Conditional Expression

I have a SSIS package that reads data from a flat file and loads it into database table. The flat file should send valid values for all columns. However, I got the file with "NULL" written for integer values. The requirement was to store NULL values in the database column.

Passing NULL in SSIS is not straight forward. The MSDN article recommends using the expression NULL(DT_STR,10,1252) to return NULL.
http://msdn.microsoft.com/en-us/library/ms141758.aspx

This did not work for me. After some work, I figured that you have to again cast the NULL return value to string to make it work.
(DT_STR,10,1252)NULL(DT_STR,10,1252)

If you want to use this in Conditional expression, you can use the following format.
Pts_Earned == "NULL" ? (DT_STR,10,1252)NULL(DT_STR,10,1252) : Pts_Earned
The above expression means if it finds "NULL" string in the column Pts_Earned it will pass on NULL or else passes on the actual value.

Hope this helps.