r - Trouble relying on third party package imports in my package -

my package uses ggplot2 extensively make custom plots. import ggplot2 in namespace file. can build, install, , load package r without errors. when call function package, complains can't find function in imported package. function called had absolute nothing plotting , didn't make use of ggplot2. how can make function calls package work without these types of errors?

error in theme_beata() (from plot.r#14) : not find function "theme_classic"

the first function erroring is:

#' custom ggplot2 theme beata #' @import ggplot2 #' @family themes #' inheritparams ggplot2::theme_classic #' @export theme_beata <- function(base_size = 14, base_family="serif", ticks = true) {      ret <- theme_classic() +       theme(axis.line = element_line(size=0.6),             axis.text = element_text(size = base_size),             axis.title = element_text(size= base_size + 2),             title = element_text(size=base_size + 4))     if (!ticks) {         ret <- ret + theme(axis.ticks = element_blank())     }     ret } 

i using devtools , roxygen2 document package. discovered getting error when running document().

> document() updating pkg documentation loading pkg error in theme_beata() (from plot.r#11) : not find function "theme_classic" > traceback() 13: theme_beata() 12: as.vector(y) 11: setdiff(names(theme_gray()), names(new)) 10: ggplot2::theme_set(theme_beata()) @ plot.r#25 9: eval(expr, envir, enclos) 8: eval(exprs[i], envir) 7: source_one(file, envir = envir) 6: source_many(paths, env) 5: force(code) 4: in_dir(file.path(pkg$path, "r"), source_many(paths, env)) 3: load_code(pkg) 2: load_all(pkg) 1: document() 

from reading hadley's book on packaging, don't think description matters in terms of exports, below bottom part:

depends: r (>= 3.1.0) license: file license lazydata: false imports:     dplyr (>= 0.4.0),     tidyr (>= 0.1.0),     xlconnect,     pryr,     stringr,     devemf,     assertthat,     grid,     ggplot2,     ggthemes,     ggally,     broom,     scales suggests:     lattice 

my namespace has following imports:

import(xlconnect) import(dplyr) import(ggplot2) import(ggthemes) import(stringr) import(tidyr)