Mr. Massey's book is a valuable reference work, but his listing of Confederate veterans' graves does contain some mistakes, mostly in terms of inference. A good example is the grave of W. H. Parker, where he matches the name on the marker with similar names in the Index of Arkansas Confederate Soldiers. Such speculative matches are often wrong and tend to muddy the research waters.
The W. H. Parker of Co. F, 1st Arkansas Mounted Rifles, was a St. Francis County man who was killed at Wilson's Creek on August 10, 1861. The W. H. Parker who served in Co. E, 38th Arkansas Infantry, was almost certainly a Randolph County man of the same name.
Such indices are useful, but unless the compiler has thoroughly researched the soldiers, instead of just matching similar names, it cannot be considered authoritative. And it's obvious that speculative name-matching is involved here, or he wouldn't have cited a soldier with that name who was killed in 1861 as a possibility for a man who died in 1908.
Although it's difficult for serious researchers to imagine it, such speculation is often used as citation by wishful thinkers for ordering VA markers. It happens more often than most of us care to think.