LambertW function in HP PRIME simulator

[robmio]

Hi everyone, as I was preparing to program my HP PRIME for Cox's regression, I found myself solving this equation:

solve (x / (1-a ^ x) = b).

The real calculator gives no result: "[]", while the simulator solves the equation with the Lambert function: LambertW. However, the "LambertW (number)" command does not give any results.
Curious, right?

See the attachment.