The TES revealed last week that North primary school in Colchester, Essex, was refusing to implement the deal, which guarantees teachers 10 per cent of their time away from the classroom for preparation and planning.
Dr Collins said: "The school has the interests of children at heart. It needs more support to make this work. Schools want to put the agreement in place but without jeopardising the quality of their educational experience."
Last week Ralph Tabberer, chief executive of the Teacher Training Agency, which has overall charge of the reforms, admitted that some schools would not meet the September deadline of allowing teachers 10 per cent planning, preparation and assessment time but said they would not face sanctions.
Classroom teacher unions have said the deal is statutory and schools cannot opt out. And a monitoring group has previously warned it was keeping an eye on the situation in Wales, following concerns that some heads were "being resistant".
Dr Collins was speaking after a conference in Birmingham attended by Derek Twigg, a Westminster education minister. One head of a small primary in Cumbria said she had struggled to implement the agreement when she spent 80 per cent of her own time teaching.
Mr Twigg said: "We recognise that it is difficult and are trying to make it better."
The National Association of Head Teachers will hold an extraordinary general meeting in London on March 16 when members will decide whether to withdraw from the deal over funding.