Good Morning.
Successful tomato growing relies on pollination and plenty of
sunshine. From past experienece tomatoes grown 'indoors' (greenhouse?)
require help with pollination. By far the best way for this to happen
is by insects - just open the windows/door of your greenhouse and let
the bees and flies do their work. So many blooms can be damaged by an
inexperienced human.

Hope you are successful,
Helen