Confused about if statement in R: Want to make conditional NA

I am confused about the conditional if statement in R.

What I want:

Let's say there are two variables; Data$Export & Data$Sales,

Only if both Data$Export & Data$Sales for a row has the value '0', I want the row to be removed from the dataset. Or, as I thought, to set any variable in the row to NA, which will consequently be removed with: "Data <- na.omit(Data) " anyway.

Therefore, I thought of the following construction:

for (i in 1:nrow(Data)) { if ( (Data$Sales[i] == 0) &(Data$Export[i] == 0 ) ) {Data$Sales [i] <- NA }} Data <- na.omit(Data)

However, this does not work, the error code yields: missing value where TRUE/FALSE needed

Thank you in advance for any help I may receive.

Kind regards, Anouk