I tried carrying out some methylation analysis using the COHCAP pipeline in R, but i am getting this error

filtered.sites <- COHCAP.site(sample.file, beta.table1, project.name, project.folder, ref="parental") [1] "Reading Sample Description File...." [1] 485512 8 [1] 485512 8 [1] "Differential Methylation Stats for 2 Groups with Reference" Error in t.test.default(group1, group2) : data are essentially constant

Can anyone help me out please????