Error message "Error in .. : could not find function .." [closed]

I wrote a user-defined function in a .R file.

 lm_Forecast=function(d,h){


  if (ncol(d)>=1){
    d<-d[complete.cases(d),]

    #lmmod <- lm(d$`Gross Sales` ~  paste(colnames(d)[2:length(colnames(d))], collapse = "+") , data = d[1:(nrow(d)-h),])

    lmmod <- lm(d$`Gross Sales` ~ Inflation  Food+ lagged_price  , data = d[1:(nrow(d)-h),])


    summary(lmmod)
    print(colnames(d))
    AIC(lmmod)

    fcst <- predict(lmmod,d[(nrow(d)-h+1):nrow(d),])
    #a<-data.frame(a=valid$Gross.Sales,   p=predict)
    #mean(abs(fcst/d[nrow(d)-h+1:nrow(d),]$Gross.Sales-1))




    #fcst=forecast(fitArima,xreg=xreg[(length(x)+1):(length(x)+h),])$mean

  } else {


    fcst=mean(d)

  }
  print("lm model")
  summary(lmmod)
  return(fcst)


}

I am then invoking it as

j=lm_Forecast(d,Horizon)

from within the same file after the function definition.

I get the error

 Error in lm_Forecast(d, Horizon) : could not find function "lm_Forecast"

despite the function being clearly present in the file before the statement that invokes it. Can anybody help me debug this? Thank you.