"Multiple-step OLE DB ... errors" on ADO PutValue

[joleary]

[VC++ 6.0, SQL Server]
I get the this error when I execute the last line of the following code:

"Multiple-step OLE DB operation generated errors. Check each OLE DB value, if available. No work was done."

CString csState = "MA";
BYTE* bt = new BYTE [256]
	for (int i = 0; i < 256; i++)  //my initialization for testing
	{
		bt[i] = i + 1;
	}
BSTR bstrBuff = SysAllocStringLen((LPOLESTR)bt,256);

pRst->Fields->GetItem("state")->Value = (_bstr_t) csState;
pRst->Fields->GetItem("data")->Value = bstrBuff;

The assignment of 'state' [varchar(2)] is OK. When csState has 3 characters, I get the same error.

A recurring theme in the forum(s) for this error around this kind of operation is:
the value is not suitable for the field to store.

The database field 'data' is declared as varchar(600). I also tried varbinary(600).

So, I am at a loss for an explanation.

Thanks for any thoughts,

jim

EDIT: corrected the bug in my code example.
Perhaps a buggy example doesn't warrant a response.
I am completely stalled on this.
Does any body have an idea?
Thanks,
jim