By using univariate analysis (McNamer/Wilcoxon), I found that there is no statistical difference between case and control groups (checked for one of my dichotomous independent variable).

When I used COXREG (in order to create consitional log regression in SPSS) and analysed the same independent variable (analysed alone in regression) - I realized there was a difference between case and control groups.

To sum up - I found a different statisticall significant while using univariate and COXREG (conditional log regression) analysis (for the same variable).

What could be my mistake?