The invention relates to embodiments of a method and a system for monitoring the correct positioning of a test element in a test element receptacle of an analysis unit, the test element carrying a sample to be analyzed by the analysis unit. Using a delimiting element, responsive signals resulting from irradiating an analysis region on the test element are effectively prevented from impinging upon a signal detector when the analysis region is in an incorrect position relative to the analysis unit. The delimiting element is provided with a light-opaque region and a light-transmissive region, and the light-opaque region is positioned such that responsive signals impinge upon it rather than the light-transmissive region when the analysis region is in an incorrect position. The embodiments of the invention further relate to methods and systems configured to further analyze the sample, to determine whether the sample has been underdosed, and additional position monitoring steps comprising irradiating different partial regions of the analysis region and comparing the detection signals responsive to each to a predetermined limit value.