If your physical credit card doesn't work

I had a interesting problem with my credit card. I have a local grocery store I been able to use it everywhere else except this one grocery store. This has been for over 2 weeks. My girlfriend just used my physical credit card 3 business away on the same street for her Salon visit. So as a experiment I went to the same grocery store and used my same credit card on my phone. It went through without a problem. So if your have a problem with your physical credit card try using your cellphone. I had also checked with my bank they said there should be a problem. Hope this helps