Evaluation request

[KateA]

My oldest daughter has had an IEP since she was 3 related to a gene duplication. Recently my youngest daughter (kindergarten, same gene duplication) is showing some of the same behaviors and/or learning difficulties. I previously expressed some concerns and was met with wait and see, so I did. At the last parent teacher conference we discussed her limited retention and difficulty paying attention. We discussed retention for another year in kindergarten and I advised I would speak with our pediatrician to see what his thoughts were. An evaluation was completed and determined she has adhd, medication was prescribed and the pediatrician requested that the school also evaluate her. 
 

Why would a school provide pushback on a request for a psycho educational evaluation and advise that retaining to kindergarten for another year is the intervention rather than receiving special educational services?