HP 17Bii LET & GET misunderstanding?

[jthole]

Probably a rookie mistake on my part, but I don't see why this calculation doesn't work:

MX = L(D:HM-HR)x0,95+HR+0xL(FR:G(D)x0,8+HR)+0xL(WL:G(D)x0,65+HR)+0x(FR+WL)

MX = heart rate threshold
HM = maximum heart rate
HR = resting heart rate
FR = fitness range
WL = weight loss range

When entering HM and HR (179 and 43, in my case) I get the correct value for MX. But when I try to display the value for FR or WL, I get "SOLUTION NOT FOUND".

What am I missing here? Thanks a lot!