I know exactly who you are talking about... I am a member of ICBM and was in attendance in Tulsa when Lindsay Roberts received the word from God that the girl would live. Benny laid hands on her and said she would not die. Several months later she died.
I believe it does more damage for us NOT to answer the question. Either the Word works or it doesn't. If it doesn't appear to work, it is not God's fault - so it has to be on our human end.
To say, as these parents now go around the country saying, "well, yes, we prayed but our daughter didn't get healed in this life... however she got the 'ultimate healing'" is a cop-out.
WOFers believe the Word. It would be far better to say they missed it somewhere than to do that "oh, you never know what that God will do".

That puts us in the same category as those who teach about Casino God - maybe He will, maybe He won't.
(FYI, folks, I have asked for an icon change to WOF.... )
But is it possible, just possible, that we do not understand the Word like we should?
For example, the Jews read the book of Isaiah and believed that the Messiah would come and liberate them from Roman oppression. When the Messiah came and died on a Roman cross, they couldn't believe their eyes. And so they rejected Christ.
If they had truly understood the Word, they would have accepted Christ. But because they thought they understood the Word already, they were not open to what God was doing.
Now, to some extent, we all have a bit of pride when it comes to our understanding of things religious. We all are pretty set in our ways. And certainly, being set in one's way makes it difficult for the Devil to come and take away one's faith. But it also makes it difficult for God to come in and make one's faith grow.
Many years ago, a particular WoF preacher lost his daughter in a tragic accident. She and her WoF preacher husband died in a plane crash. Naturally, this loss was devistating. Beyond the personal loss, however, were questions not unlike the ones raised herewith: Did God fail or did the preacher's faith fail?
I wondered myself. Then I learned that about ten years before this crash, the mother and daughter had had a conversation about airplanes. The mother was concerned about her daughter's safety as she and her husband flew from city to city. The daughter said that she was not afraid of being in a plane crash. In fact, she said, she would much rather be in a plane crash with her husband than to be a widow without him.
I recounted this to a WoF friend who works for a major ministry. My friend immediately replied that the plane crash must have been a product of the lady's bad confession. Now, that may well be the case, but I think the answer may be more simple than that. This woman's hearts desire was to die with her husband. I believe that God granted her desire.
Now, this brings me back to my original point. The death of the aforesaid little girl may have nothing to do with doubt or unbelief. The little girl may well have seen a glimpse of God's glory and decided that she wanted to go home.
If this were indeed the case, does this make the Word not work? If she wanted to go home, then did God fail by not healing her? Conversely, if she wanted to go home, did her parent's faith fail?
I am not saying that this is the reason she died. For all I know, she may have been praying to live up until the very moment she died. I don't know.
But what I do know is that there is a reason--a reason which may transcend our two-dimensional theological paradigm. And if we continue to force everything we see or hear into this theological construct, we may end up doing what the Jews did. We may know the Word (Scripture) inside and out, but still miss the Word (Jesus) when He walks in our midsts.