I was printing on a A4 thick (invitacion Card)

Make sure there is 1/16 to 1/32 inch space on each side of the paper in the paper tray.
Move the paper type selector back and forth 5 times, to make sure it is not stuck.
Feed the tray with a minimum of 20 sheets of paper and try to see if it loads paper through.
The paper thickness lever has two settings, one for plain paper, (thin paper 20# to 24#) and one for envelopes and thick paper.
It should be on the 0 setting for thin paper and on the + setting for thick paper and envelopes.
The paper adjustment lever may be adjusted in between the two settings to accommodate paper that is not standard or that the operating/environmental conditions have changed.
Make sure the paper is loaded far enough into the printer to ensure good contact between the paper and the paper feed mechanism.