Weird thing happens to me when I do runs

Hi

so the weirdest thing happens to me when I do runs is that when I practiced a certain run it comes weird when I put it in a song do you understand me ? I don't know how to describe this but it sound weird when I put the run that I practiced in a song..

Like for example in Bruno Mars song (when I was your Man) in the verse part where he sings "take you to every party, cause all you wanted to do was dance" the run in the word "dance" I can do it perfectly when I practiced the word "dance" in a run alone but when I use it in the song the transition between "was" and "dance" comes a little bit weird like there's a small teeny tiny stop between "was" and "dance" but I know that I'm not stopping it but it just happen.. 

I hope you understood my problem because I really don't know what it is plus english is not my first language so it was really hard for me to describe the problem that I'm having

thank you

That makes sense, Manar! I'd practice that full line slowly, without music - and make sure you're certain of the interval between "was" and "dance". You can get it!