A couple of things come to mind. First, WISC VCI doesn't equate to a reading level. My dyslexic ds20 would be a prime example of that. He scored quite well despite his reading levels. For example, the comprehension subtest is measure responses to general ideas or social situations. In no way represents what most people think of comprehension.
DRA has been a nightmare for us. My dd6 scored grade level most of the year. The school stock to the party line of "it is a comprehension issue." They tested her on WIAT & WJ the comprehension score was >99.9 %tile. She was not giving them enough of a response on the DRA. If she is bored she will give responses like "it's about a dog." Which on an assessment like DRA is a score killer. I measure her reading by the books she reads at home and how well she can answer questions about them. When she loves a book I hear endlessly about it. She finally scored somewhat closer at level 28 in March, still off because its now written responses and she has some difficulty with writing in general. Add salt to the wound, the school wants to take credit for her growth from a level 4 in Sept to 28 in March! She was reading level 28 at home in Sept, Sigh...