I have a analysis in edgeR, but it ended by error. This is my data:

Sample  treat   factor1 factor2
s1  CT  1   c1
s2  CT  1   c2
s3  CT  2   c3
s4  CT  2   c4
s5  CT  1   c2
s6  CT  2   c3
s7  CT  2   c4
s8  CT  1   c5
s9  CT  1   c6
s10 CT  2   c7
s11 treatmetn   2   c3
s12 treatmetn   2   c4
s13 treatmetn   1   c5
s14 treatmetn   2   c6
s15 treatmetn   1   c7
s16 treatmetn   2   c8
s17 treatmetn   1   c9
s18 treatmetn   2   c4
s19 treatmetn   2   c5
s20 treatmetn   2   c6
s21 treatmetn   1   c7
s22 treatmetn   2   c8

I used this formula for analysis

 --formula "treat+factor1+factor2" \

at the end I have this error:

Error in glmFit.default(sely, design, offset = seloffset, dispersion = 0.05, : Design matrix not of full rank. The following coefficients not estimable: factor2C8 Calls: estimateDisp ... estimateDisp -> estimateDisp.default -> glmFit -> glmFit.default Execution halted