[R] error for using igraph library: 'edges' must be numeric or character

[Zahra Tofighi]

hello, i want to use igraph  for drawing graph of my data. First time i try
do it and it was successful. but now i want to test again i got this error:
"edges must be numeric or character". this is my edge list(this is output
from R):
            From            To
1  US20100331312
2  US20100331341
3  US20100330919 US20100041339
4  US20100330919 US20100195590
5  US20100330919 US20110170512
6  US20100330919 US20110312368
7  US20100330919 US20110021152
8  US20100330919 US20110026376
9  US20100330919 US20110028097
10 US20100330919 US20110028098
11 US20100330919 US20110028100
12 US20100330919 US20110028107
13 US20100330919 US20120083303
14 US20100330919 US20120100883
15 US20100330919 US20140038659
16 US20100330919 US20140162715
17 US20100330919 US20150049721
18 US20100330919 US20150257156

 I'm sure they are character. what's my wrong?
with Regard,

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