Cucumbers need warmth to flower as well as nitrogen and phosphorus and sunshine. If your squash is making blooms then your soil is fertile, but it could be your soil is not acid enough for cucumbers due to the excess of fertilizer. Check the pH or acidity of the soil. For cucumbers it should be around 6.5. If you overfed and the soil is above 7 from a pH test then try adding lots of water to flush out the excess nitrogen. You can also add calcium to adjust the pH of the soil. One more thing. Another thought is it could just too early for your cucumbers to make blooms. Warm days encourage male cucumber flowers and then cooler temperatures ensure female flowers will follow the male blooms. Female flowers are the ones attached to a small fruit while males just have a stem.  You did not say where you garden. A location with cooler nights and warmer days is ideal. Perhaps the greenhouse is too warm at night? Keeping the doors and windows open may help and also allow pollinating insects in to move the pollen once the flowers do appear.  Sometimes just waiting a few more weeks will solve the problem when flowers suddenly appear.  Keep growing, Marianne Binetti