Help me with setting blocks!!

[MusicManSK]

Hello!
This is my first post on this website because Im need help and here i found many solutions of another problems thats I fixed! But actual problem is that i have 2 positions seted into variables and i want to set specific blocks between this two positions but after running command nothing happens. Im desperate because i waste hours of fining some solutions or something, but still nothing. Here is code that I made:

loop blocks within {lf.pos1} and {lf.pos2}:
    set loop-block to blue clay

or this:

loop blocks between {lf.pos1} and {lf.pos2}:
    set loop-block to blue clay

I tried everythig, every combination. Im really desperate. Plzz help me .
Thanks for answers!

 

[Lego_freak1999]

I need code where you set THE variables

 

[Soufreur78]

Use: "loop blocks within {lf.pos1} to {lf.pos2}:"

 

[MusicManSK]

Use: "loop blocks within {lf.pos1} to {lf.pos2}:"

@Soufreur78 thx! works! but... I think I tried this way but idk. thx so much!