topomap calibration

Hi

I am not sure we van poste here, topomap is not and "orux product" .. but i will try

try to explain in english

when i make a map with topomap i saw at the border of the map a bleue area.

i a make asecond mao, which is with same coordinate to have two maps neighbor. But that's not true, it have these blue area and not a
continuity between the two maps

any idea ?