I'm trying to run linear regressions between my genotypes and phenotype, but I keep getting an error, which I'm not familiar with...

My model is: res1 <- snp.rhs.estimates(formula=as.formula(paste(phenotype, "~ 1")), family="gaussian", data=pheno, snp.data=genotypes, uncertain = TRUE) 

and the error is:  Error in terms.formula(formula, special, data = data) :    invalid term in model formula

Any insight would be appreciated! Thanks!