\documentclass[12pt]{leter}
\usepackage[paperwidth=2.25in, paperheight=4in, margin=1mm, textwidth=1.85in]{geometry} % Define paper stock size here
\special{papersize=2in,3.75in}
\usepackage{etoolbox}
\pagenumbering{gobble}
\usepackage{tabularx}
\usepackage{graphicx}
\usepackage[code=Code39,X=.275mm,ratio=2.25,H=.5cm]{makebarcode}
\newcommand\finline[3][]{\begin{myfont}[#1]{#2}#3\end{myfont}}
\usepackage{times}
\begin{document}
\newcommand{\PrintOne}[2]
{
\isblank{#2}{#1}{#2}
}
\pdfpagewidth 2.5in
\vspace{2mm}
{\Large \textbf{bin}}
\hfill
{\Large \textbf{number}}
\vspace{2mm}
\hline
\vspace{2mm}
\centerline{\barcode{number}}
\\
{\Large \centerline{\testbf{ABC-Store}} \par}
\\
{\tiny \centerline {\textbf{DIGITAL OFFICE SOLUTIONS}} \par}}
\vspace{2mm}
\hline
\PrintOne{description}{itemnotes}
\\
\small{description}
\\
Please email -------@----------.com 24 hours a day or Call 204-555-1212 between 8:00am 4:00pm to reorder. Please reference the Bio-Static serial number from the yellow label on your copier.
\\
\newpage
\end{document}
What it does is print a 2.25x4 label with a bar code, and then I want it to print one of the two variables in the \PrintOne function. for some reason all it does it crash with an error from the calling program. If I take out the \usepackage{etoolbox} and the \PrintOne everything prints. But it prints too much, I only want one of the \PrintOne to print.

leterclass? Do you meanletter? Sorry, this document seems to be a mess. There's a stray\hlinewithouttabularenvironment which breaks the code already – Jun 03 '15 at 15:15letertoletterthe document stops with an error on\hline(which is only valid in tables) but that error seems to be unrelated to the problem you describe. Please fix the example so that it does not have unrelated errors to give people a chance to see the intended problem. – David Carlisle Jun 03 '15 at 15:20\ifblank, not\isblank– Jun 03 '15 at 15:21