Good readers ask themselves questions as they read and organize the information in some manner (e.g., main ideas and details) for easier retrieval. They monitor their understanding, using "fix up" strategies (e.g., rereading, clarifying difficult vocabulary, reviewing text structure, making a mental movie as they read) to help themselves if they get off track.
Although you may have some insights into what's going wrong for your daughter, the only way you can be sure is by having a reading specialist have a look at her to see what, if any, strategies are actively in place to aid comprehension. Once you know for sure what she's doing, then you can plan support to meet her specific needs. Excellent information on reading comprehension and resources for reading strategies can be found on LD Online (www.ldonline.org) in the "In Depth" or "For Teachers" links.