Tex output - unwanted subscript "t"

Hello two professors, I got a similar problem with lead of model local variables.That is , I have several model local variables, which are to be added into the model equations in the lead or lag form.
Unfortunately, Dynare stops running and gives an error warning:
ERROR: DSGE_model.mod: line 611, cols 19-27: Model local variable X_P cannot be given a lead or a lag.
Since some of the model local variables are complicated expressions, I do need the lead or lag form to simplify the expression in my model. Is there any way to solve this issue? I need your help, thank you in advance.