Question: Warning, solutions may have been lost

Hi, I have the following equation and I would like to solve the equation "EQN" for n with 0<taut<1 and 0<taum<1 but I received not only a solution but also the warning "solutions may have been lost". I wonder why.

The equation is:

> EQN:=6581019.044*n*(ln(3.*(6110.-1811.*n+1980.*n*taum+1200.*n*taut-7800.*taum-7800.*taut)/(-25423.*n+28140.*n*taum+18000.*n*taut+74230.-101400.*taum-117000.*taut))/(10000.-1000.*n)^(3/4)/taum)^(50/13)-.2407407407*ln(3.*(6110.-1811.*n+1980.*n*taum+1200.*n*taut-7800.*taum-7800.*taut)/(-25423.*n+28140.*n*taum+18000.*n*taut+74230.-101400.*taum-117000.*taut))/taum = 0;

>UUU:=solve(EQN,n);

Warning, solutions may have been lost

UUU:=(130. (-43. + 60. taum + 72. taut))/ ( -1999. + 2220. taum + 1440. taut)

Many thanks for any of your advice.