xlateStrSubstring error

Team,

I’m trying to pull the first three numbers from PV1.18 (Patient ID) for comparison and possible supression.

I did the following:

xlateStrSubstring 0 2

and am getting the following error in the testing tool:

MESSAGE 1
Tcl callout error
xlateStrSubstring 0 3:

errorCode: NONE

errorInfo:
bad type “nm”: must be c, d, v, or x
while executing
“xpmstore $xlateId $outAdd $outType [string range $inValue $_first $_last]”
(procedure “xlateStrSubstring” line 15)
invoked from within
“xlateStrSubstring 0 3”
<End of errorInfo>

Why??