Problem setting VI_ATTR_SUPPRESS_END_EN Attribute for my TCPIP MBSession

[morsecode]

using NationalInstruments.Visa;

using Ivi.Visa;

mbSession = (MessageBasedSession)rmSession.Open(sr.ResourceName);

((INativeVisaSession)mbSession).SetAttributeBoolean(NativeVisaAttribute.SuppressEndEnabled, false);