PLINK2 software problem

[Akki-akki]

Dear all:
There is a tough problem for me: I want to merge all imputed_data and INFO data that given from UKBB. but i fail to merge, can somebody tell me that's wrong with my code or do you have other idea about how to merge it?
my code in below:
plink2 --bgen /disk/disk1/UKB/Gene/Imputation/ukb_imp_chr${chr}_v3.bgen 'ref-first' --sample /disk/disk1/UKB/Gene/Imputation/sampleID.sample --extract-col-cond ukb_mfi_chr${chr}_v3.txt 8 2 --extract-col-cond-min 0.5 --make-pgen --out out