JOEL - Actually Joseph was only praying to God the Father. Some of the early leaders of the Church sometimes used the name "Jehovah" as they spoke about or to God the Father, using it as a title rather than a name. Another example is in the following prayer of Joseph Smith:
"O Thou, who seest and knowest the hearts of all men - Thou eternal, omnipotent, omniscient, and omnipresent Jehovah - God - Thou Eloheim, that sittest, as saith the Psalmist, "enthroned in heaven," look down upon Thy servant Joseph at this time; and let faith on the name of Thy Son Jesus Christ, to a greater degree than Thy servant ever yet has enjoyed, be conferred upon him..."(Joseph Smith. History of the Church. Vol.5. p.127)
More recently in the church we have avoided using the term "Jehovah" for God the Father to help avoid confusion about who we are talking about. This also happens a few time in the Old Testament where some prophets refer to God the Father as "Jehovah". This is part of the reason why there is some confusion about who the God of the Old Testament really was. But in most cases in the scriptures the name "Jehovah", is obviously refering to Jesus Christ. Please see the following web page for more explanation:
http://www.mormonhaven.com/devin.htm
Our prayers should always be directed to our Father in Heaven in the name of Jesus Christ . (Matt. 6:9, Luke 11:2, D&C 18:18) It is God the Father who, as the father of our spirits, is responsible for answering our prayers. He is the Supreme Being. So out of respect for Him, it is to Him that our prayers should be directed.