wkhtmltopdf is not generating PDF properly

I'm using wkhtmltopdf to generate PDF and observed that PDF is generating fine in the development environment and Testing environment but UAT environment is not generating the PDF properly sometimes.

Passing the header and footer by using command-line arguments as --header-html and --footer-html

Observed Issues(Not happening often):
The header is missing
PDF is getting broken from the body

We are using the following Version:
wkhtmltopdf 0.12.5
Qt 4.8.7

Can somebody help me to resolve this issue?

Regards,
Muthuraja