we are growing sugar baby & black diamond watermelons in Galveston County, Texas. they get enough sun and they have been growing from seed and seedlings for over 4 months. they look ripe but when we cut them, they are white or mostly white & some red inside, not wholly red and ripe. what is the issue? we've only gotten a few good ones, most of them have all the signs and length of time correct to be ripe, but aren't. thank you.