Here is a refutation of one of the reasons for doubting that Daniel was a Prophet:
(Full Article Here with other Objections)
First, a technical objection is sometimes made that Daniel was placed in the "Writings" and not the "Prophets." Hamner [Hamn.Dan, 1; see also DilHart.BDan, 25] writes:
The Hebrew canon consists of three divisions, the 'Law', the 'Prophets', and the 'writings', and Daniel is included in the third and last division. This suggests that the book was not known by 200 B.C. , about the time when the collection of prophetic writings was assembled.
And Driver [Driv.BD, xivii-xiviii] said earlier:
...there are strong reasons for thinking that the threefold division represents three stages in the collection and canonization of the sacred books of the O.T.,--the Pent. being canonized first, then the 'Prophets' (in the Jewish sense of the expression), and lastly the Kethubim. The collection of the 'Prophets' could hardly have been completed before the third century B.C.; and had the Book of Daniel existed at the time, and been believed to be the work of a prophet, it is difficult not to think that it would have ranked accordingly, and been included with the writings of the other prophets.
In response to this objection, Archer [Arch.DEx, 7-8] writes:
As for the placement of Daniel in the Masoretic arrangement of the canon, this is completely without evidential force. Writing in the east first century A.D. Josephus made the following statement concerning the Hebrew canon (Contra Apion I, 38-39 [8]): 'We do not possess myriads of inconsistent books, conflicting with each other. Our books, those which are justly accredited, are but two and twenty, and contain the record of all time.' He then broke these twenty-two books down into three categories: five books of Moses (ie., the Pentateuch), thirteen books of the Prophets, and the remaining four books that 'embrace hymns to God and counsels for men for the conduct of life.' The four books of poetry and wisdom were unquestionably Psalms, Job, Proverbs, and Ecclesiastes. These four constituted the entire third division of the canon---the Writings---in Josephus's day, rather than the thirteen assigned to it by the Masoretes of the late first millennium A.D.
As for the thirteen books of the Prophets, as recognized in the first century A.D., they were apparently the Former Prophets, including Joshua, Judges-Ruth, the two books of Samuel, the two books of Kings, the two books of Chronicles, Isaiah, Jeremiah-Lamentations, Ezekiel, Daniel (which were classified by the second century B.C. LXXs Major Prophets), the Twelve Minor Prophets as one volume (since they could all be included in one large scroll), Song of Solomon, Ezra-Nehemiah, and Esther. There is no possibility that Josephus could have regarded Daniel as belonging to the Writings. Very clearly he included it among the Prophets, along with Solomon's prophetic parable of love (S of Songs) and the exilic and postexilic books of history, all of which were composed from a prophetic perspective. Therefore, we are forced to conclude that the Masoretic division of the canon, coming as it did six or seven centuries after Flavius Josephus, has no bearing whatever on the date of Daniel's composition or on its status as a truly prophetic work.
And Whitcomb [Whit.BD, 15-6] adds:
Most conservative Old Testament scholars believe that Daniel was not placed among the prophets in our present Hebrew Bible because he served in a foreign court, did not prophesy directly to the people of Israel, and included much historical material in the book. But, significant evidence is available that Daniel was originally counted among the prophets and was only shifted to another category of canonical books of Hebrew scribes in the fourth century A.D.
First, Daniel was listed among the prophets in the Septuagint translation (hence the position of our English Bibles through the medium of the Vulgate). Second, Josephus (first century A.D.) listed Daniel among the prophets. Third, Melito, bishop of Sardis (A.D.70), did the same. Fourth, Origen (d. A.D. 254) listed Daniel before Ezekiel and the twelve prophets. R. Laird Harris thus argues not only for the full canonicity of the book of Daniel but also its inclusion among the prophetic books in the most ancient Hebrew collections.
And Archer says elsewhere [Arch.SOT, 388-9]:
The Masoretes may have been influenced in this reassignment by the consideration that Daniel was not appointed or ordained as a prophet, but remained a civil servant under the prevailing government throughout his entire career. Second, a large percentage of his writings does not bear the character of prophecy, but rather history (Chap.1-6), such as does not appear in any of the books of the canonical prophets. Little of what Daniel wrote is couched in the form of a message from God relayed through the mouth of His spokesman.
These findings are confirmed by Koch [Koch.DanP], who points out that Daniel was regarded as being among the prophets in the NT, in the LXX, and at Qumran. The shift to the Writings, he says, was not until the 5th-8th century AD.
