How to insert null value into a table using typed dataset???

I m using typed data set to insert some record into table. if the data type of 1 of da column is Byte and allow null is "true". then how to insert null value into that columns??? In table adaper that column property "Allow Db null is true. but when i pass the "null" as  parameter, it through the  "wrong parameter" error. even i ve set that parametes nullable. Is there any way to insert the null value....

suggest some solution  ...
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