boxcox.fit error

Hi,

Thakns all for your help

I am doing the next in my dataframe tabla, column pend1, because the
Lilliefors (Kolmogorov-Smirnov) test give me a pvalue < alfa. (data no
normal distribution). I need do a transformation with box-cox or
other:

bc <- boxcox.fit(tabla$pend1)

R send to me:
Error in boxcox.fit(tabla$pend1) : Transformation requires positive data

The summary for my data is:

summary(tabla$pend1)

Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
    0.0    12.8    19.8    20.2    27.2    57.9

length(tabla$pend1)

[1] 4408

Someone can help me?. What is the error?

Thanks

Alexys H