为什么我的第二个sqlite表抛出异常？

我有创建表的DatabaseHelper类。第一张表（录音）工作正常，但第二个表格（录音）正在尝试使用它时插入异常（插入/选择...）。为什么我的第二个sqlite表抛出异常？

这里距离DatabaseHelper我的代码：

public void onCreate(SQLiteDatabase db) { 

    String createTable="CREATE TABLE recordings" + 
      "(_id INTEGER PRIMARY KEY AUTOINCREMENT," + 
      " name VARCHAR(255) NOT NULL," + 
      " datestart VARCHAR(255) NOT NULL" + 
      ")"; 

    String createTable2="CREATE TABLE recording_image" + 
      "(_id INTEGER PRIMARY KEY AUTOINCREMENT," + 
      "imageurl VARCHAR(255) NOT NULL," + 
      "imagetime INTEGER NOT NULL," + 
      "prot_id INTEGER NOT NULL," + 
      "FOREIGN KEY(prot_id) REFERENCES recordings(_id) ON DELETE CASCADE" + 
      ")"; 

    db.execSQL(createTable);  
    db.execSQL(createTable2); 
}

唯一的例外是：