matlab中taylor展开错误

wanglidong007

>> syms x c m n
>> syms B
>> y=B*(1-exp(-c*x))^m

y =

B*(1 - 1/exp(c*x))^m

>> taylor(y,B)

ans =

B*(1 - 1/exp(c*x))^m

>> taylor(y,c)
??? Error using ==> mupadmex
Error in MuPAD command: B*(1 - exp(-c*x))^m does not have a Taylor series expansion,
try 'series' [taylor]

Error in ==> sym.taylor at 63
  t = mupadmex('symobj::taylor',f.s,x.s,a.s,int2str(n));
上面是我计算的过程，在计算在c处的taylor展开时提示错误，请问怎么解决？谢谢！