CreateADOStoredProc and a adVarChar Parameter

exec ZipStoreConversions @ProductId=N'GMVE 000057',@ParameterCollectionID=N'FH',@ConvertToProduct=N'VIT 000100',@ConvertFromProduct=N''



parameters definiod from stored procedure

@ProductID varchar(11),

@ParameterCollectionID varchar(50),

@ConvertToProduct varchar(11),

@ConvertFromProduct varchar(11)



I use following code  - it always give me error in line 

param1["DataType"] = DB["adVarChar"];

"Arguments are of the wrong type, are out of acceptable range, or are in conflict with one another"





Do I do something wrong?

Cmd["CommandText"]= "dbo.ZipStoreConversions"

Cmd["CommandType"] = DB["adCmdStoredProc"];

var param1 = Cmd["Parameters"]["AddParameter"]();

param1["Name"] = "ProductId";

param1["DataType"] = DB["adVarChar"];

param1["Direction"] = DB["adParamInput"];

param1["Value"] = "GMVE 000057";

var param2 = Cmd["Parameters"]["AddParameter"]();

param2["Name"] = "ParameterCollectionID";

param2["DataType"] = DB["adVarChar"];

param2["Direction"] = DB["adParamInput"];

param2["Value"] = "FH";

var param3 = Cmd["Parameters"]["AddParameter"]();

param3["Name"] = "ConvertToProduct";

param3["DataType"] = DB["adVarChar"];

param3["Direction"] = DB["adParamInput"];

param3["Value"] = "VIT 000100";

var param4 = Cmd["Parameters"]["AddParameter"]();

param4["Name"] = "ConvertFromProduct";

param4["DataType"] = DB["adVarChar"];

param4["Direction"] = DB["adParamInput"];

param4["Value"] = "";

RecSet = Cmd["Execute"]();