no sis, to see jannah in a dream is much possible, becoz u can see MUCH GREATER as examplified below.
"One of the highest examples of such favor is undoubtedly the meeting and true vision of the Prophet, which is a reality established in the hadith of seeing the Prophet in dream, and documented through the relations of the trustworthy from the Companions to the Successors and their Successors down to our day. Some of these relations have been recorded in Suyuti's fatwa Tanwir al-halak fi imkan ru'yat al-nabi wal malak (The illumination of intense darkness through the possibility of seeing the prophet and the angels) in his Hawi li al-fatawi. We have already mentioned in the section discussing the evidence that the Prophet hears and sees us al-Haytami's answer in his Fatawa hadithiyya whereby it is possible for Allah's Friends to meet the Prophet while awake in our time.44 They can also meet al-Khidr, as Sakhawi relates about Imam Nawawi:
It is well-known that he (Imam Nawawi) used to meet with al-Khidr and converse with him among many other mukashafat.45
The exalted status of the saints' firasa is mentioned in the hadith whereby the Prophet said: ittaqu firasat al-mu'min fa innahu yara bi nurillah "Beware the vision of the believer, for he sees with the light of Allah," then he recited the verse: "Therein lie portents for those who read the signs" (al-mutawassimin) (15:75).46 Tirmidhi narrated this authentic hadith in the Book of the Commentary of Qur'an in his Sunan and said that some of the commentators have explained "Those who read the signs" as meaning: those who possess vision (al-mutafarrisin)." al-Sakhawi in al-Maqasid al-hasana (#23) mentions another authentic hadith whereby the Prophet said: "Allah has servants who know (the truth about people) through reading the signs" (tawassum).47"
45 al-Sakhawi, Tarjimat shaykh al-islam qutb al-awliya Abi Zakariyya al-Nawawi, p. 33.
46 Tirmidhi (gharib) from Abu Sa`id al-Khudri, and Tabarani from Abu Imama with a fair (hasan) chain according to al-Haythami in the chapter on firasa of Majma` al-zawa'id.
47 Related from Anas with a fair chain by al-Bazzar, Tabarani, Abu Nu`aym in al-Tibb al-nabawi, and from Ibn Sa`id by Bukhari in his Tarikh, al-`Askari in al-Amthal, Ibn Jarir al-Tabari in his Tafsir for 15:75, Ibn Abi Hatim, and Ibn Mardawayh.