It's also helpful to integrate visual cues with verbal cues to help receptive language along a little bit. In your treasure hunt games, you can show the child pictures of where something is hidden as well as tell her where it's hidden. Eventually, see if the child can find it without the pictures, relying on the verbal clues along. This practice is very useful if the child simply has some unevenness in the way different parts of her nervous system are developing. Her expressive functions may be developing faster than her receptive ones.
Different skills develop at different rates in different children.
When there are receptive language problems, it's always a good idea to make sure the child is hearing properly. Consider an audiological evaluation, even if the child is obviously hearing some things. Some children hear loud sounds at certain frequencies, but not at others. Other children may be oversensitive to certain sound frequencies. A number of other medical problems can contribute to receptive language delays, so it's always wise to recommend to parents that the child have a general pediatric evaluation as well.