According to Longuenesse, the savage cannot recognize a house as a house not only because he lacks the concept but also because he misses the schema (an essential condition for developing a concept). The savage receives the same sensory information on the house as someone familiar with the concept of a house does but he does not possess the procedure to process the information in a determinate way. Here’s an excerpt from Longuenesse’s book (Page 119):
"Kant's savage intuits a combination of sensations according to relations of contiguity in space, differences in color, light, and shadow, similar in "matter" to those intuited by "someone else" who knows that what he has before him is a house. Thus, in his intuition of the house, the "savage" is conscious of the "combination of representations with each other." He is also conscious of a relation of these representations "to (his) senses," that is, conscious of them not merely as presenting an object to him but as sensations within him, perhaps associated with feelings of pleasure or displeasure. But the system of comparisons into which the content of his intuition is channeled has nothing in common with ours. He has never seen anything similar (in the way "a spruce, a willow, and a linden" are similar) from which he could have obtained a common concept by comparing objects according to their similarities and differences, reflecting similar features and abstracting from the differences (in material, size, shape, and so on). In his apprehension there is no rule guiding him to privilege certain marks and leave aside others, so that a concept of house might apply. Should someone point to the object and call it 'house', this might suggest to him a proper name for the singular object he has in front of him, but even this is uncertain: how is he to know what is being referred to—the door, the color, the shape, the site, or what? Only the "application in a comparison," that is, the gradually dawning consciousness of a "rule of apprehension" common to the representation of various objects serving the same purpose, would pick out analogous marks and bring forth the concept of a house. This application alone will complement the intuition of Kant's savage with a discursive form similar to that acquired by the man who throughout his life passed his nights in a warm house in Königsberg."
In the above passage, it's to be noted that Longuenesse says that “there is no rule guiding him to privilege certain marks and leave aside others, so that a concept of house might apply.” This means that, according to Kant, in order to recognize a thing a human being needs not only the concept of the thing but also the precondition for acquiring the concept of the thing, namely its schemata.