This study deals with semantic problems of communication. It concentrates on common semantic problems in human-computer and human-human interaction. Two different methods, the method of Schank (in the area of computational linguistics) and the method of Jackson (in the area of linguistics) are analysed and their meta-models, in terms of object-oriented approaches, are presented for the purpose of comparison. Despite their complexity, none of the methods are able to cope with the problem of ambiguity in communication. A simple example is used to analyse and illustrate this problem in terms of conceptual models. Analysis of a complex sentence is done to show the problem of relativity of the semantic roles.