Work permit extension

Hi, I had Sweden work permit from March 2017 but I traveled to Sweden for the project in October 2018. My work permit is expiring in March 2019, so I have applied for extension, will there be issue in extension since I did not travel on work permit in first one and half years while it was valid??
My personal number application was denied for this reason and they asked me to reapply after I get work permit extension.

Ideally you should not have problem with extension if your employer have done all their part correctly and you have provided all your information correctly. I think Personnel number application is denied correctly because if you can't get extension you might not complete 180  days, which make you eligible for being taxed.