How to solve " Some vertex names in edge list are not listed in vertex data frame" in plotting Social Network Analysis

Question

I have made my edge file and nodes :

edges<-structure(list(source = c("a", "a", "a", "a", "a", "a", "a", 
"a", "b", "b", "b", "b", "b", "b", "c", "c", "c", "c", "c", "c", 
"c", "d", "d", "d", "d", "d", "d", "d", "d", "d", "d", "d", "e", 
"e", "e", "e", "e", "e", "e", "e", "e"), target = c("CONCEPT-OF-SELF", 
"ENERGY", "SLEEP-SYMPTOMS", "ATTENTION", "COGNITIVE-ABILITY-THING", 
"COGNITIVE-CONTROL", "COGNITIVE-IMPAIRMENT-THING", "CONCEPT-OF-SELF", 
"DELUSIONS", "DEMENTIA", "EXECUTIVE-SYSMPTOMS", "LANGUAGE-ABILITY-THING", 
"LEARNED-COGNITIVE-ABILITY", "LOSS-OF-CONSCIOSNESS", "MEMORY-LOSS", 
"NEGETIVE-MOOD-AFFECTIVITY", "SUICIDAL-IDEATION", "COPE", "INTERPERSONAL-TRUMA", 
"INTERPERSONAL", "POOT-PYSCHOSOCAL-FUNCTION", "SOCIAL-PROCESS", 
"ENERGY", "DEMENTIA", "IMPUSIVITY", "LANGUAGE-ABILITY-THING", 
"LOSS-OF-CONSCIOSNESS", "RECOGNITION-THING", "NEGETIVE-MOOD-AFFECTIVITY", 
"APPROACH-MOTIVATION", "PERSONAL-MANNER-THING", "EXECUTIVE-SYMPTOMS", 
"DELUSIONS", "DEMENTIA", "EXECUTIVE-SYSMPTOMS", "LANGUAGE-ABILITY-THING", 
"LEARNED-COGNITIVE-ABILITY", "DEMENTIA", "IMPUSIVITY", "LANGUAGE-ABILITY-THING", 
"LOSS-OF-CONSCIOSNESS"), X = c(NA, NA, NA, NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
NA), weight = c(7L, 37L, 13L, 85L, 9L, 36L, 4L, 5L, 19L, 1L, 
10L, 1L, 2L, 36L, 161L, 2L, 3L, 1L, 1L, 19L, 56L, 6L, 1L, 10L, 
70L, 56L, 18L, 4L, 1L, 2L, 12L, 20L, 5L, 8L, 5L, 2L, 6L, 6L, 
12L, 19L, 20L)), class = "data.frame", row.names = c(NA, -41L
))

nodes<-structure(list(ID = 1:31, name = c("a", "b", "c", "d", "e", "CONCEPT-OF-SELF", 
"ENERGY", "SLEEP-SYMPTOMS", "ATTENTION", "COGNITIVE-ABILITY-THING", 
"COGNITIVE-CONTROL", "COGNITIVE-IMPAIRMENT-THING", "DELUSIONS", 
"DEMENTIA", "EXECUTIVE-SYSMPTOMS", "LANGUAGE-ABILITY-THING", 
"LEARNED-COGNITIVE-ABILITY", "LOSS-OF-CONSCIOSNESS", "MEMORY-LOSS", 
"NEGETIVE-MOOD-AFFECTIVITY", "SUICIDAL-IDEATION", "COPE", "INTERPERSONAL-TRUMA", 
"INTERPERSONAL", "POOT-PYSCHOSOCAL-FUNCTION", "SOCIAL-PROCESS", 
"IMPUSIVITY", "RECOGNITION-THING", "APPROACH-MOTIVATION", "PERSONAL-MANNER-THING", 
"EXECUTIVE-SYMPTOMS")), row.names = c(NA, -31L), class = "data.frame")

I used this code from "igraph" package to plot my social network :

g <- graph_from_data_frame(d=edges, vertices=nodes, directed=FALSE)

However, I got the following error while I used all the sources and target in my vertices file:

Error in graph_from_data_frame(d = edges, vertices = nodes, directed = FALSE) : 
  Some vertex names in edge list are not listed in vertex data frame

Could you please help me how to identify values are not listed vertex data frame as my main data set is bigger than sample.