The reality is for some kids it does take longer.
My elder DD was almost 8 before she was reading with any confidence and ability.
I would always do home reading programs, but it got to a point where DD was just getting a chip on her shoulder about not being able to read. Every night was a battle so I made the decision to stop forcing it for a while, I waited for her to grow up a bit.
Once she was nearly 8 the summer before yr 3 I set a challenge and said ok now we need to start reading everyday, it was hard but we stuck to it and she began to progress.
By 8 she started reading books for pleasure, discovering a series she loved, after that I would always get her books from the library, anything I thought she might like or graphic novels just to keep the momentum going (I still do this now).
She is now 11 and reading is a favourite pastime she loves adventure/fantasy, so lots of Percy Jackson, Keeper of the Lost Cities, Fable Haven etc
So my advice is relax about it for now, gentle encouragement try to find books they enjoy. 6 is very young, practice sight words.
The first books my DD really enjoyed reading were One Fish Two Fish and Hop on Pop by Dr Suess, they are fun and a great place to start building confidence. Also the Elephant and Piggie books are hilarious and good for sight words.