Oh no! That's not good. If you bought light tubes, it may be that the tube is incompatible with the fixture. Please double check the rating of the fixture (is it a T5 fixture? T8? T10, T12?) and make sure that the tubes you've purchased are the same size! Please note that the included tombstones will fit your tube perfectly.
If the size/length is correct but the ending type is not, please note that though purchases of our 4ft SEP tubes include matching tombstones, that all of our tubes (except our 8ft tube) will have dual-pin endings. Our 8ft tube has a single-pin ending. If you plan on plugging the tubes directly into the fixture without tombstones, please check and see that the fixture takes the correct pin endings for the tubes you've purchased.
If you bought bulbs, it may be a couple of different things – base size and diameter are big factors. For base sizes, our E26 base matches most American screw-in sockets. We also offer a smaller E12 screw-in size for chandelier bulbs, and several pin-base bulbs (GU5.3, GU10, GU24 and G24q). Please check your fixture and see what type of base it requires. If the diameter is too wide, we suggest that you purchase a similar style bulb in a smaller size (noted by the number after the bulb name – ex. BR30 is smaller than BR40) in order to fit it into the fixture.