Randomized Response with R (package rr)

I'm fitting a logistic regression using a Randomized Response variable with the 'rr' package in R. I have two predictors, a continuous variable and a dummy and I would like to put the interaction term in the model. This is the code`

      rrreg(formula=RRT_Fox~D_Score + Damage + D_score*Damage, p=2/6, p0=2/6, p1=2/6, design="forced-known", data=df,
        maxIter = 10000, verbose = FALSE, optim = FALSE, em.converge = 10^(-8), glmMaxIter =
          10000, solve.tolerance = .Machine$double.eps)

However, the interaction term is not well accepted by R, which tells me that :

Error in solve.default(information.rr, tol = solve.tolerance) : system is computationally singular: reciprocal condition number = 3.97411e-17 In addition: There were 14 warnings (use warnings() to see them)

Why doesn't it handle the interaction term? It deals perfectly with multiple variables.

Jacopo