Bulk Insert with Null Value

I'm having trouble inserting null value from a bulk insert statement.

The first Row inserted successfully,but the second not.i also checked with CHECK_CONSTRAINTS,but the problem remains

please help me

Here is an extract of the csv file:

First Name, Last Name, AgeName1,HK,23Name2,YH,

Here the bulk Insert statement:

Bulk insert dbsct 
FROM 'C:\Test1\dstd.CSV'
WITH (
    FIRSTROW = 2,
    FIELDTERMINATOR =',',
    ROWTERMINATOR = '\n'
    KEEPNULLS
    )