I just made a Adaboost Classifier with these parameters,
1.n_estimators = 50
2.base_estimator = svc ( which is a support vector classifier )
3.learning_
A little late to answer your question, but I had a similar experience recently. In my case though, I realised I wasn't scaling the X before using SVM as the base estimator. Just make sure you scale the data from 0 to 1 (StandardScaler() from sklearn can be used) which is always required prior to using SVM.