Ahmad the unusual thing is that Afghan Taliban attacking Pakistani check post which proves if true
1. Pakistan is not helping Afghan Taliban so they are angry over it and attacking us.
2. If ISI, Pak army as per claims of some elements in US and India, supports Afghan Taliban then why they would attack us in the first place ?
3. How will such attack on Pakistani post will help Afghan Taliban in their fight against NATO/US?
it is difficulto to say anything in this stage, but at least we dont have any reports to have included ANA in this attack, on the other hand Afghani taliban have claimed responsibility, for the bolded parts of your post, it is worth to read this interview with a taliban commondar:
For a Taliban commander fighting well-resourced foreign forces, help from the Pakistani intelligence service is a shameful necessity.
the militant agreed to meet the Guardian in one of Kabul's ritziest restaurants, in a hotel-shopping complex, where he bemoaned the ISI's influence.
"Whoever disrespects your country and interferes in it is your enemy, but sometimes you need to ask for help from your enemies," said the wiry 52-year-old, as he scooped up food with bark-like hands, hardened by his day job as a farmer.
Because of orders "from superiors" to talk to foreign media, he had been prepared to travel by taxi for several hours from his village. He passed easily through the extra security laid on for the second day of President Hamid Karzai's peace jirga – a gathering he said was controlled by the Afghan president's foreign backers and was therefore pointless.
As with the nine Taliban field commanders who met the author of the LSE report on the ISI's connections to the Taliban, he spoke freely about his unease at the role of Pakistan's spy agency, which he blamed for attacks where ordinary Afghans were killed or hurt.
He said: "We do everything we can to avoid civilian causalities. But there are different types of Taliban – there are those like me and there are those that follow direction from the ISI. Those are the kind that kill elders and attack schools. They don't want to have schools in this society. They want to keep Afghanistan in the darkness of no education."
Some western officials hope that such anti-Pakistani sentiment will encourage some insurgents to stop fighting as part of a "reconciliation" process. One senior diplomat recently said that the two greatest inducements to Taliban fighters were the opportunity to return home from Pakistan and to get out of the grip of the ISI.
The arrest in Pakistan of a former senior Taliban commander, Mullah Baradar, in February is now regarded by analysts as a bid by the ISI to prevent the Afghan Taliban from unilaterally opening peace talks with Karzai's government.
The commander who spoke to the Guardian interpreted things slightly differently, but still saw it as an example of Pakistan's untrustworthiness. "They handed over one of best operations people in exchange for lots of dollars," he said.
"On the one side they are helping us, but on the other side when the Americans pay more money they hand him over."
some of the commander's explanations might explain things a bit.