# Validity of stepwise regression in DistLM

I have a set of nutrient fluxes data and I would like to know which environmental drivers explains the fluxes. I used DistLM and the marginal test showed that none of the independent variables were significantly different (p<0.05) however one did come close (C:N ratio, p = 0.07). The sequential tests for the stepwise model showed that after adding C:N ratio to the model, 2 other variables contributes significantly to the model. Is the stepwise still valid even though the C:N ratio was not significant in the marginal test?