Many players are reporting this problem.
One OFP player claims that there are 2 snipers that you must finish off. One of the snipers may be in the woods nearest the base to the north.
OFP player Nyles postulates that the only tricky thing was to take the camp in the ruins at the end of the mission, coordinating the attack with your two supporting tanks. He had to wait several minutes after the area was secure and then a small counterattack had to be fought back.
For OFP players Greg Nichols, Seed and others, the problem was caused by two BMPs, at around coordinates EE33, approaching the camp from the northeast that were getting stuck driving up a hill. They were stuck about half to 3/4 of the way to a village in the northeaster named Dolina. After taking out the two BMPs, the mission ended for these players. OFP player Louis Carresi believes that the BMPs only get stuck if your TERRAIN DETAIL video setting is set above NORMAL.
If that doesn't solve your problem, you're simply going to have to either use the ENDMISSION cheat or install a complete copy of the RESISTANCE.SQC file and revert to the next mission, Counterattack.