Without knowing your fields, planting methods, and weather it's hard to say.
I am NOT an expert on crop planting and stuff but I do have experience with Timothy and Orchard Grass cause it's what I've used on my place for years.
Timothy and OG have very small seeds and it needs to be planted close to the surface. Push a Timothy seed two inches deep an you arent gonna get anything from it cause the seedhead doesnt store enough energy to get it up out of the ground.
1/4 inch planting depth is best in my experience.
They need to stay moist too which can be tricky because of the shallow planting depth.
Timothy will basically stop growing in the summer heat....Orchard Grass slows down a lot but will keep growing most of the year and tolerates a fair ammount of shade.
Both of these grasses prefer cooler weather which is why they are so popular up here in New York.
Like I said I don't know your area, the fields, or the weather, and you might already know all of this.
I would certainly want to figure out why the seed didn't come up before I planted more of it.
Timothy has a shallow root system too so gotta be careful using it for pasture. Makes great hay though