stange

im passing a dataset to a webservice and then on the webservice side im looping the ds and performing an insert for each record when all columns are nvarchar, this currently works fine, so this part of the process is cool,

I then change col 1 to be vbinary and pass encrypted info works fine for column 1,2 but when i go to encrypt column 3 it gives stange errors like

convert invalid cast dbnull to string,
the col is varbinary, and also sometimes i get dbnull to dbnull errors

the only difference i see is column 1 & 2 dosnt show <null> if i return 1000 rows in sql server but col 3 does ?

any ideas would be good if you can come back to me about it

ps encyption is done on the webservice side not before