Sqlite query syntax error

I have a sqlite query for search like this:

c = db.rawQuery("SELECT Task.* FROM Task where Task.CreationDate >= '" + strStartDate + "'  ORDER BY Task._id ASC", null);

but I have this Error :

SQLiteLog(4733): (1) near ">": syntax error

what is the problem? how I must write this query? type of CreationDate is TEXT, and strStartDate is like '2012-04-05'