使用sybase提供程序sybase.adonet4.aseclient在c#ado.net中运行writetext sql命令时出错。我试过很多不同的方法，例如使用parameterindex、命名参数等等。有人能帮我吗？我在下面展示示例代码。

AseConnection cn = new AseConnection(connection.ConnectionString);
cn.Open();

//..... there is other code here that calls a stored procedure and gets textpointer 
// reference, but I am leaving it out to keep it short and simple

AseCommand cmd2 = new AseCommand("writetext mytable.column1 @textPointer @bigText", cn);
cmd2.CommandType = CommandType.Text

cmd2.Parameters.Add(new AseParameter("@textPointer", AseDbType.VarBinary, 16));
cmd2.Parameters["textPointer"].value = textPointerOut.value

cmd2.Parameters.Add(new AseParameter("@bigText", AseDbType.Text));
cmd2.Parameters["bigText"].value = bigText;

cmd2.ExecuteNonQuery();

cmd2.executenoquery（）引发异常，错误为必须声明变量@textpointer
更新：如果我尝试下面的语法，我会在'@bigtext'附近得到一个错误的sntax

AseCommand cmd2 = new AseCommand("{writetext mytable.column1 @textPointer @bigText}", cn);