The charity says discrimination is commonplace and gives examples of children being refused school places, or being excluded, because of the condition.
The NCB's HIV Network and the National Aids Trust had been pressing the Department for Children, Schools and Families (DCSF) for better guidance for schools on how to support HIV-positive children.
But despite support from teaching unions no consensus has been reached.
Maria Phelan, co-ordinator at the NCB's Children and Young People HIV Network, said the campaign has shifted to individual MPs.
A DCSF spokeswoman said: "The Department does not think it is necessary to publish any new guidance at this stage.
"Implementing the Disability Discrimination Act in Schools and Early Years Settings was issued in 2006 and this provides interactive support and advice for schools on how they should implement the duties outlined in the Disability Discrimination Act 2005.
"This guidance is necessarily generic to take into account the broad spectrum of disabilities as defined in the Disability Discrimination Act 2005, which includes HIV and Aids."
She added that following discussions with the National Aids Trust, an internet link to guidance produced by the trust for teachers has been added to the Teachernet website
