INSERT into inserting only three characters after truncation

[S N]

I was using an INSERT into statement to insert records into an access
database which was working alright.
However, ever since I am using the same SQL statement to insert records into
SQL server database (nothing has changed except the connection string and
schema information), the INSERT into statement is inserting data of only
first three characters into one particular field , instead of 5 or 7
characters as is being inserted in the form in asp page. The SQL server
database field is character type (nvarchar) .
I have checked the form values being submitted from the asp page and the
values are getting submitted alright, still the database is getting only the
first three characters from the field. When I use the same asp page to insert
into the access database, it again inserts all the data without any
truncation.
Please advise on how to insert all the characters in the SQL server database
field.