Hello,My guess is that you are trying to say you get erections but unable to perform?Some times a vaginismus leading to contractions of the vagina may make it very difficult to achieve a penetration.So also lack of secretions of the partner may not make way due to poor lubrication.Performance
anxiety from your side may again lead to poor penetration.May be this answers your question?Cheers.
Dr.M.Jagesh kamath MBBS. Dvd Consultant dermatologist