Is it compulsory for the Madrasah to pay backdated rent according to Shariah?

Madrasah Madania Talim-ul-Islam 11.12.07 Respected Mufi Sahib اسّلام عليكم ورحمة الله وبركاته We would like to ask a Shari Ruling regarding rent for a Madrasah which is based at an Islamic Secondary school building, the Islamic Secondary school building was opened by the current Chairman and the current Vice Chairman (a committee was later made on the bases that they would be supportive). Currently the Madrasah uses three classes in the evening for Madrasah. The Madrasah currently pay’s rent. But the issue has arisen about rent for the Madrasah when it first opened in 2004. Before the Madrasah opened, eminent scholars gave Mushwerah that the building was not used in the evenings and it would be suitable for evening Madrasah, through this it was then decided by the Chairman that the building can be used without any rent being paid, this was due to the Madrasah being new and to get the Madrasah running, at this time none of the Governors of the school were active in the daily issues of the school. From 2006 due to some issues (regarding the Islamic Secondary school) the Governors of the school got involved and they raised the issue of rent and they decided that rent should be back dated to (2004) and paid to the date of when payment first started (which was 2006). According to Shariah is it compulsory to for the Madrasah to pay the backdated rent? مدرسہ مدنیّہ تعلیم الاسلام