Database INSERT problems

I am trying to insert in a SQL database using the following command:
OleDbCommand objCmd = new OleDbCommand(string.Format("INSERT INTO MEMBER (MEMBER_ID, PASSWORD) VALUES ('{0}', '{1}')", txtJangee.Text, txtPassword.Text), objConn);
 
when i run the code i get the following error:

The statement has been terminated.
Cannot insert the value NULL into column 'LAST_NAME', table 'master.dbo.MEMBER'; column does not allow nulls. INSERT fails.However I am not attempting to insert anything into the LAST_NAME column, could anyone give me any insight into what could be throwing this error.
 Thanks - Matt

 
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