Cannot extract a valid token from a string from AMESim

Dear all, I have a AMESim S-Function in my simulink model. There's an error when I try to creat .sdf for real time application by using "build model" : extract a valid token from the string x/hydrComplianceGear<Unable to interpret the value for expression 'x/hydrComplianceGear'>.

The 'x/hydrComplianceGear' is the expression of FX00(output a prescribed function of input) in my AMESim Model and the global parameter hydrComplianceGear is 1e-6. I changed the espression into x/(1e-6) and there's no errors any more. As this parameter has nether the longst name, nor the smallst value, I have no idea about this error.

Any suggestions? Thx!