help with a custom move command...?

I have attached my custom version of the "move" command.. but I need
some help with it..

the point of this lisp version is to allow for imerial distances when in
a metric drawing.. and it almost works 100% of the time..

when in a metric drawing and you enter an imperial distance in polar
format (@1'<45) the lisp dies.. and it also dies if you enter in
relative format (@1',1').

There must be a way to alow for this type of input (without having to
toggle the drawing units from metric to imerial)..

HELP!?

(defun c:move (/ mset Perror dimset tarunit mp1 mp2 mp1dist 1evom 2evom mp2dist)
(setvar "cmdecho" 0)
(setq PERROR *error*)
(setq *error* ETRAPMO)
(setq dimset (CDR (ASSOC 1 (dictsearch (namedobjdict) "XRECLIST"))))
(if (= dimset nil)
(if (= (getvar "lunits") 2)(setq tarunit 25.4)(setq tarunit 1))
(if (= (substr dimset 4 1) "M")(setq tarunit 25.4)(setq tarunit 1))
)
(= (SETQ MSET (SSGET)) NIL); Select objects (use currently selected objects):
(while (/= 1evom 1)
(initget 128)
(setq mp1 (getpoint "\nSpecify base point or displacement: "))
(cond
((= (type mp1) 'LIST)
(setq 1evom 1)
)
((= (type mp1) 'STR)
(progn
(SETQ mp1dis (distof mp1 4))
(if (/= mp1dis nil)
(progn
(setq 1evom 1)
(setq mp1dis (* tarunit mp1dis))
(setq mp1 mp1dis)
)
)
)
)
)
)
(while (/= 2evom 1)
(initget 128)
(setq cgrips (getvar "grips"))
(setvar "grips" 0)
(sssetfirst mset mset)
(setq mp2 (acet-ss-drag-move mset mp1 "Specify second base point of displacement or <use first point as displacement>: " highlight 0))
; (setq mp2 (getpoint mp1 "Specify second base point of displacement or <use first point as displacement>: "))
(sssetfirst)
(setvar "grips" cgrips)
(cond
((= (type mp2) nil)
(progn
(setq 2evom 1)
(setq mp2 mp1)
)
)
((= (type mp2) 'LIST)
(setq 2evom 1)
)
((= (type mp2) 'STR)
(progn
(SETQ mp2dis (distof mp2 4))
(if (/= mp2dis nil)
(progn
(setq 2evom 1)
(setq mp2dis (* tarunit mp2dis))
(setq mp2 mp2dis)
)
)
)
)
)
)
(command ".move" mset "" mp1 mp2)(princ)
(setvar "cmdecho" 1)(princ)
)

(defun ETRAPMO (msg)
(setvar "cmdecho" 0)
(if (or (= msg "Function cancelled") (= msg "quit / exit abort"))
(princ)
(princ (strcat "\nError: " msg))
)
(setq 1evom nil)
(setq 2evom nil)
(setq mset nil)
(setq mp1 nil)
(setq mp2 nil)
(prompt "\n")
(setq *error* PERROR)
(setvar "cmdecho" 1)
(princ)
)