So confused! Please help!!

I just switched ovulation tests from the clearblue digital ADVANCED test to the regular clearblue digital test. This morning at around 7:45 am it showed an LH surge (smiley face), when I took it again this evening it was solid circle (no smiley face). Is it possible the surge this morning was a false surge or in 12 hours my surge is gone?? I feel so confused and this is my 8th month trying to conceive.