st: xtprobit and dummy var

[ncdcta00@uniroma2.it]

Dears,
I made an estimation of female participation with xtprobit, because I  
have a panel data, in my estimation I have the education and children  
(dummy var) for female , the income for family and the education (  
dummy)and unemployment  benefit for the husband, plus dummies for time
but when the probit running , stata drop all variables refere to  
husband for collinearity. why?

xtprobit active agefem age2f eduf1 eduf2 eduf3 chl12f ch06f ch03f    
logincome  cedu1 cedu2 cedu3 hwork  hump dum2 dum3 dum4 dum5 dum6 dum7  
dum8 if country==2, re i(id)

thanks for help

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